We watched Dunkirk, and wondered how many military deaths are for reasons more of logistics than of facing the enemy. Probably lots - we have heard that war is made of colossal logistical feats, so probably they often fail, and often lives depend on them.

(Imagine organizing a party with hundreds of thousands of people at it. Imagine that is located in an overseas country, where you don’t have a house, and everyone hates you. Imagine that it goes for several years. Imagine it is a very stressful party for the partygoers, but also you are counting on them to carry out some hard and terrifying tasks for you during the party. Imagine you anticipate many deaths during the proceedings.)

Which made me wonder, why is war so centrally planned? Why wouldn’t all these logistical details be simpler and cheaper in the usual ways if each soldier looked after himself mostly? Similar to how it works better for each person to look after themselves during peacetime, rather than having commanders organize and dictate the whole peaceful existence effort. Thoughts?

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I recommend the book Supplying War, by Martin Van Creveld. It is on the official reading list for United States military officers, and covers the history of military logistics, mostly in Europe, from the Napoleonic Era through WWII.

The insight most relevant to the question is that until WW1, most armies essentially did leave each soldier to look after themselves. This method of supplying the army is called 'forage' which means that the army spreads out and acquires supplies through whatever means (sometimes commerce, often plunder and rapine). In WWI this changed, for two reasons according to Van Creveld:

  • The equipment was sufficiently different between the belligerents that they couldn't just pick it up and use it anymore. In the Revolutionary War and the Napoleonic Wars, you could just take the enemy cannon, turn them around, and bring them to the next battle. But by WWI the guns all used different ammunition, different powder strengths, and required at least a modicum of training to operate effectively.
  • Highly developed rail systems finally allowed enough bulk transport to actually meet the needs of the army. Previous attempts at overland logistical support had all been failures: every army in European history depended more on forage than they did on overland supply trains, until WWI. Example: Napoleon's invasion of Russia is widely known to have overextended the French supply lines, and the Russians deployed 'scorched earth' tactics (which means to burn your own stuff so the enemy cannot have it) resulting in the defeat of the invasion. This is wrong: the French supply lines were never a significant factor, and further the scorched earth tactics did not succeed; the French army was able to get a satisfactory amount of forage from the Russian country side regardless. The casualties came during the retreat over already-foraged land; it was the cold that killed them.

So during and after WWI, a military needs to make sure it has enough stuff, that it can use, so that it can continue to prosecute the war. This cannot be accomplished by every soldier looking after themselves; they will run out of ammunition, cannot fix their broken weapons or vehicles; etc.

However, it is absolutely possible for there to be too much central planning, and this problem is centuries old. Covered in the book is the case of Operation Overlord, the legendary assault on the western shores of Europe to invade the Third Reich. It is a tale of horror, and of heroic courage; the moment in the popular mind when the war turned and the Allies effectively ensured final victory. It was also a logistical catastrophe. Unprecedented efforts went into the planning of assault, down to exactly how many cans of gas were required for each jeep, which is precisely where they went wrong. In the chaos of the invasion, whole armies landed miles away from where they were expected; armies landing nearer supply depots meant for different armies used them as a matter of necessity. The Allies did not succeed in their objectives the first day; in places ammunition ran short and vehicles ran out of fuel. The invasion nearly failed. Fortunately recovery was swift; 160,000 men were in the assault in June; 2,000,000 were in Europe by August, on the strength of a tenuous foothold the first day.

Cycling back to the initial question, how many people die in war as a consequence of logistics vs. enemy action: almost all. The largest killer of soldiers across history by far is disease; typhoid, dysentery, malaria, etc. The lack of sufficient food and shelter increases vulnerability to disease; the lack of good hygiene guarantees disease; the lack of good medical care increases the fatalities from disease. All of these are logistical questions. Since the health and equipment of soldiers has a huge impact on whether they win engagements, logistics remains a large factor in how many deaths result from enemy action, as well.

Addendum for a broader interpretation of centrally planned that includes stuff like hierarchy and strategy: information management is basically the reason. When soldiers disperse to forage, it takes a long time to get them back together again such that they are militarily effective; catching the enemy army at forage is extremely advantageous and practically guarantees winning. In the modern era, armies grew to the population of whole cities; this is too huge a burden for local resources to sustain in most places.

So the problem becomes how to keep them watered, fed and equipped, while simultaneously keeping them in close enough communication that they can coordinate to do the job they were sent for.

Interestingly this is an active area of inquiry for the US Army now: the reason is that we were in recent decades able to conduct operations almost free from interference because of air and naval supremacy, but we cannot take that for granted in a new regime of electronic warfare and area denial weapons. This has lead to the investigation of swarm tactics; the pitch for the individual soldiers is that instead of central coordination they operate under a small ruleset which tells what to do in various tactical situations. The goal is to mimic self-organizing systems in biology.

Also the word they have chosen for how these units are going to communicate is called "stigmergy" which is hilarious to me for some reason.

I think each soldier looking after himself was the older model some centuries ago, and maybe still is in place in many civil war situations (to the detriment of the civilian population). However, within the current international humanitarian rules of law it seems to be quite difficult to do that.

And for modern maneuver warfare based on fast troop movements I don't see how soldiers could organize their own supplies.

It doesn't look like "each person looking after themselves" works better in peace time either. 

Dictatorships screw up horribly for a large number of causes, but if you look between democracies, the states where the governments intervene the most to ensure the livelihood of their citizens are the ones better off.

A peacetime where every people look after themselves would mean no taxes, no public transportations, no public services. You want safety? You have to buy yourselves a gun. Health? Even insurance is a collective deal (and it works way worse than public healthcare, if you see the ratios between health and costs of healthcare), you'd have to have enough moneys in your pockets to actually pay for your doctor visits, operations, etc...

 

In warfare, if you remove central logistic, each soldier have to buy or "obtain" what he need by himself. Soldiers would be bidding against each other, the local sellers would increase prices (this is all considering the buy option and not the "obtain" which... yeah) and local shortages that bring to disaster become much more likely, especially since large number of soldiers often have to be moved quickly to new areas with no room to worry whether that area could sustain them or not.

Even if you imagine a central transportation system being put in place and a central buyer from which soldiers are encouraged to buy what they need, you'd get a lot of problems because individual and group foresight would be pretty low. ("We knew Russia was cold, we didn't expect it was so cold! Could you get us 100000 heavier coats and shoes within, say, three days? Most of us should still have toes by then").

 

Generally, individual people are absolutely horrible at preventing problems, preventing problems is unbelievably cheaper than solving them, and central organisations have a lot more ways to see problems coming and prevent them. In warfare, the cost of problems and lack of foresight is a lot higher. 

Ideally you'd also want central organisations to be evaluated using the individuals feedback ("How much are you, U.S soldier in the Vietnam war, satisfied with the M16 assault rifle? Which problems did you experienced using it? Being dead means you automatically gave the worst possible score") to fix all the kind of problems you run into by using central organisations, and some emergency procedure to fix the problems if central organisation seem to have screwed up big time.

 

Mostly I think the problem is where you set the line, the question is a bit vague on where to draw boundaries on individual efforts and central organisations.

Individuals may be bad at foresight, but if there's predictably going to be a good price for 100000 coats in a few months, someone's likely to supply them, unless of course there's some anti "price gouging" legislation.

Part of the issue is the predictably, I feel. The Russian winter example is pretty obvious now, but I doubt french coat makers really had more chances to see the problem coming than Napoleon and his advisors. 

An industry of dedicated providers for the military could spend money to research possible wars in hope to be better informed and make profits... provided they can't make more profits in just investing more on marketing or whatever. Their goal would be to just maximise profit, and with competitors in the equation the welfare of the army starts to be less and less relevant for that.

For example: pharmaceuticals industries aren't really showing much foresight in the development of new antibiotics. The growing resistance of bacterias to antibiotics could become a really dire problem in the future, but research to develop new antibiotics is pretty expensive and unlikely to yield short-term profits. (granted, I hadn't heard governments being much more foresightful about this).

 

Part of the problem is that any corporation large enough to match the military's intelligence and research capacity is also going to suffer from badly thought incentive programs, so there's no reason to expect them to be better off. If I'm a manager evaluated on this year profits, I should be pretty "stupid" to invest in something that might yield profits ten years from now.

If you replace any goal an organisation might have with "maximise profit" there's no real reason it should yield better results than an organisation with a goal that's actually what you want. My feeling is that modern corporations are pretty close to unaligned AIs in how they're able to ignore what a human moral would expect them to act and just stick with their "maximise profit" utility function.

 

The last point of the issue is that individuals might suck at deciding what they need. 

In the case of a winter coat in the middle of the Russian winter you' have to be an idiot not to buy it, but there's no reason a soldier would pick the equipment that maximise his chances of survival, if the problem can't be seen easily. Like a gun that look cool but has higher chances to jam at the wrong moment. Other soldiers would warn you... but aren't you likely to have bought the gun before reaching them? What do you do then? You buy a new one even if it's expensive? Also, now marketing is getting involved, so there are actually five guns with "anti-jamming" mechanisms, plus the "better and improved" version of the one you have, which offers a 50% discount if you turn in your old gun... 

For example: pharmaceuticals industries aren't really showing much foresight in the development of new antibiotics. 

Giving that selling new antibiotics to most people who might want to buy them is outlawed, I don't think that's very surprising.

To give the pharmaceutical industry an incentive to develop new antibiotics it's necessary to either allow them to sell the antibiotics everyone who wants to buy them or pay them enough money for providing new drugs directly.

Selling them to people would quickly make bacterias develop a resistance to the new antibiotic, making them useless for their purpose (having a way to fight a pandemic from a strain of bacterias that developed a resistance to all available antibiotics).

I agree that this law sinks the profits to the bottom, but this was more or less my point. You can't expect private profit to match what's actually needed.

Paying them to develop the drug makes sense if it wouldn't be their intellectual property after and if it's cheaper than developing them yourself... it's still central logistic thought, I think the military always used contractors for mass orders they paid themselves. 

My feeling is that on the long term we're way better off building up the structure to carry on such  research in the public sector, but it's not relevant to the issue.

Paying them to develop the drug makes sense if it wouldn't be their intellectual property after and if it's cheaper than developing them yourself... 

Why would it make only sense if it wouldn't be their intellectual property? If the key thing you care about is access to antibiotics that kind of thinking doesn't make sense. 

However if your ideological views bias you to find things besides having antibiotics more important then it turns out that you won't get new antibiotics.

I notice that I wrote costs, while what I had in mind was more like a... contractor fee. The government pays X to the industry so Y stuff gets done. The government owns the Y stuff it paid for. 

I wasn't expecting a private industry to just do the job at 0 profits for the goodness of their hearts.

 

I apologise in advance for how much I ended up writing below. My opinions on these themes are based on a number of inferential steps and I did my best to sum it up, because I think that clearing that possible misunderstanding on "costs" still left the problem I was thinking about unmentioned. It also has no real bearing on the issue of central vs individual logistics efficiency.

 

However if your ideological views bias you to find things besides having antibiotics more important then it turns out that you won't get new antibiotics.

I can't really see it as an ideological bias, I think it's a legit worry about the state of future based on not-ideological considerations. 

First, I'm pretty concerned about policies such as "governments paying the cost for industries developing X and then such industries retain the full right to use it and profit from it as if they had shouldered the costs". 

The government sees no return whatsoever. The population suffers a loss as well, since a medication (or X) they paid for is being sold back at them at market price, rather than the production price a government could set, or the lower yet price industries would set if facing competitions.

So it feels like this is the less possible efficient usage a tax-payer could see of his moneys, basically a free handout to private industries.

Paying a contractor fee makes more sense, at least the government can try to produce value from what he paid for more effectively. It still has problems, but I guess it can be a good way to produce more value for the population.

 

My second issue is that these kind of policies hugely weakens public research over the years. 

Governments keep incurring in large expenses year after year, these expenses are likely considered as part of the research budget, but anyone working in the public research doesn't sees a dime from this, so eventually shifts to private research for lack of work and funds, and the capacity of the nation to produce public research gradually shrinks further and further.

It is the exact opposite of what taxation should do, and corporations of large enough size are basically immune to taxation already. Rather than redistributing wealth you are just concentrating them in the hands of a big private.

A government should evaluate the costs and benefits of research infrastructure in the medium run, build the infrastructure it needs if it's economically viable, and if not, look for ways to make it happen in the future while negotiating for the better terms it can get with the corporations to develop the antibiotic now, if it's needed in the short term. 

Of course, I have no clue on how to calculate costs and benefits for research infrastructure, and the vague knowledge I heard tells me it's complicated as hell.

But, if it's economically viable for a corporation to build their own research lab, I see no way it wouldn't be so for a government. 

(If anyone has detailed knowledge on why this isn't the case I might change my view on this, but there would still be no reason to not look for the best "price" you can get from corporations for the antibiotics. Why should governments be the only ones not worrying about trying to get the most value from their moneys?)

This way you can get antibiotics, thriving public research, and a population that's not growing more and more impoverished.

 

This still might not be important enough to be left without antibiotics in a deadly pandemic.

So of course, if you need the antibiotics now and have no other way that's equally efficient, negotiating with the corporation on worse terms is acceptable. But it better be an emergency-only policy, not the norm.

 

Third, I have a problem with the reliability of private research in general, (though not so in fields such as medicine, where the liabilities for missteps are too costly). 

If you go look at what research from private industries sustained on subjects such as acid rains, global warming, tobacco and such, it's clear that reality and standards gets tossed from the window as soon as they become a threat (I actually researched these claims for my thesis, I'm not talking from personal feelings like I mentioned above).

There's also the problem of intellectual property, that makes a lot more harder for science to be able to pile up if half the stuff I'd need to build on is intellectual property of someone else who acts to maximise its profits. I'm fine with giving royalties and big cash prizes to whoever deserved them, but if you don't have science that's public and can be used by everyone, I fear that science eventually just slows more and more.

To clarify: I'm not against private research, the world would be clearly a lot worse off without it and it can produce a lot of improvements for the whole mankind as it did already. But a future with more and more private research and less and less public research looks a lot worse off to me.

 

Lastly; A lot of this is coming from the background knowledge that, if you look at how the distribution of wealth has been going in the last thirty years, you can see that the wealth of the world is basically being sucked in a whirlpool of large capitals and corporations, with the rest of the population slowly having less and less. 

A key cause for it is that anyone large enough can legally stop paying taxes and does so, so he gets to reinvest a 100% of his profits to make more profits, while also receiving funds from governments to cover up large losses (or, in the case we discussed, expenses). 

(It's also pretty frustrating, if large corporations and capitals just payed taxes in the ratios the average citizen does we'd be basically swimming in a huge pile of public research and utility already.)

Anyway, the economic growth these entities are producing isn't benefiting the general populace enough to compensate just how good these entities are at making bucks at the general expense. If it was enough, we would be seeing the general population getting richer, and the big private entities getting even more richer, but only the second one is happening. 

Research shows that economic growth just stops correlating with the population welfare after a certain threshold (plenty of research on this from Wilkinson and Pickett and many others) and what determines the population wellbeing turns out to be the wealth distribution in said nation, which is getting more and more focused everywhere. 

So, to get back on my issue with this kind of policies of public funded private research, any transaction that takes public money and hands them to these entities that aren't giving back enough, just makes the problem worse, and should have some pretty amazing benefits to be considered.

 

I really have to write a sequence on this. It's a lot more efficient than occasionally spending a hour to comment on a thread.

The government sees no return whatsoever. The population suffers a loss as well, since a medication (or X) they paid for is being sold back at them at market price, rather than the production price a government could set, or the lower yet price industries would set if facing competitions.

I don't suffer if I have an antibiotic resistent infection and a company sells a drug to cure it at market price. I suffer if I have an antibiotic resistent infection and there's no drug available that cures my illness and I die.

You need a lot of ideology to the conclusion that the act of someone selling me a drug that prevents me from dying at market prices makes me suffer.

But, if it's economically viable for a corporation to build their own research lab, I see no way it wouldn't be so for a government. 

Corporations are a lot better at cutting of wasteful research that doesn't make proftis then government research labs are. The fact that free market driven enterprise is much effective then government run programs.

Research shows that economic growth just stops correlating with the population welfare after a certain threshold (plenty of research on this from Wilkinson and Pickett and many others) and what determines the population wellbeing 

The idea that lifesaving medince doesn't help population welfare seems very strange to me. Having more corporations that develop medicine for conditions that previously couldn't be treated as well clearly improve welfare. 

As a society we want developing new drugs to be more profitable then laying of researchers and doing stock buybacks because better medicine is one of the ways we can actually translate increased societal wealth into increased population welfare.

I don't suffer if I have an antibiotic resistent infection and a company sells a drug to cure it at market price. I suffer if I have an antibiotic resistent infection and there's no drug available that cures my illness and I die.

You need a lot of ideology to the conclusion that the act of someone selling me a drug that prevents me from dying at market prices makes me suffer.

I have to point out that in my last comment I specifically said that negotiating with the private company is the correct choice when the alternative is mass deaths due to the lack of antibiotics. We agree on "death due to infection is worse of having to pay market prices plus public money for development". 

It's just that I believe "using public moneys to develop X as a private resource" it's a worse long-term strategy for keeping society supplied of Xs than "use public moneys to develop X as a public resource", and I'm really not understanding why you assume there is no possible third alternative where I suffer even less because I only have to pay market prices or the costs of development, and not both. (I'm also fine with short term hybrid solutions such as "government pays half of X development costs, private agrees to keep prices at an agreed value to ensure X is easily accessible", I guess).

Since you accused me twice of coming from a biased and strongly ideological viewpoints while I sticked with practical considerations and arguments, citing no kind of rhetoric or anti-capitalistic moral to justify my position, I start to feel like I'm not the one bringing ideology into this argument.

 

Corporations are a lot better at cutting of wasteful research that doesn't make proftis then government research labs are

Corporations are way too good at cutting any research that doesn't make the most profits. This is a huge problem for research and science, because anything that might lead to huge public benefits and breakthroughs but needs 20 years of expensive research gets ignored and cut. 

Also, you focus research on what gets you profit rather than generating utility for mankind.

 

The fact that free market driven enterprise is much effective then government run programs.

Can you link me any data on this? I had saw research in different textbooks that said that public service was actually matching private enterprise for quality/costs of service in stuff like healthcare, water, light and other commodities, and in retirement investment plans. I'll try to recover it and link it since I'll need to write something on this, but I have to locate it first. Or you were referring to other types of programs?

 

The idea that lifesaving medince doesn't help population welfare seems very strange to me. Having more corporations that develop medicine for conditions that previously couldn't be treated as well clearly improve welfare. 

The key issue is that economic growth stops correlating too much to the development of lifesaving medicine after a certain point, and stops correlating to the access of the public to lifesaving medicine even faster. 

Wealth distribution, instead, correlates with access to such lifesaving medicine a lot more. The population suffers not because there is no lifesaving medicine to be bought, but because the market price of lifesaving medicine can be unreasonably high and still be the one which generates the most profits. 

I'm not managing to find accurate informations of how much antibiotics cost in the US, it seems to be twice or three times what they cost in Europe, and they still seem to be one of the cheap drugs, as I expected (I remember having bought Ofloxacin for 27€, here it's listed at 80$). Anyway, all the sources I found seem to agree that prescription drugs in the US are basically the most expensive in the world, and by a lot. https://cddep.org/tool/current_prices_antibiotics_class_age/ 

Companies likely wouldn't scalp too much on flashy stuff like the antibiotic needed to save the population from flesh eating bacterias due to getting bad press, but poor people in need of "boring less-flashy lifesaving medicines" are currently haiving to make the choice between having medicine or having a roof (If I understand correctly insulin is sold in the US 700$ a dose?). 

Corporations can develop all the lifesaving medicines they want, if the optimal profit solution is to sell them at a price only 40% of the population can afford, you won't nearly see as much benefits for the population than in a system that treats health as a public resource and sets prices to what everyone can afford.

So to link back with

I don't suffer if I have an antibiotic resistent infection and a company sells a drug to cure it at market price. I suffer if I have an antibiotic resistent infection and there's no drug available that cures my illness and I die.

You suffer if you have to choose between losing your home/sinking into debt/renouncing lots of   things needed for health to afford treatment for the antibiotic resistant infection (which, money wise, actually seems one of the best health problem you can get).

 

As a society we want developing new drugs to be more profitable then laying of researchers and doing stock buybacks because better medicine is one of the ways we can actually translate increased societal wealth into increased population welfare

This seems like the most expensive way to get new drugs ever. I have to make it so that developing new drugs is one of the most profitable things a company can do with its moneys? Either you pay as a society many times what you'd pay to develop it yourself (remember, you're paying twice already, first to cover costs with public moneys, second to buy it at market price as a population), or you systematically sink and ban all other things a corporation can do, which I don't believe would really be a good idea.

 

 

Maximising profit isn't an utility function that can be expected to be efficient at providing utility to the general population. It's an utility function that doesn't have public health at all in its parameters. 

What kind of unlikely coincidence is needed to make so that maximising profit ends up, by basically mere chance, to also improve public health more than a system with as utility function to actually improve public health?

You might find the way mercenary armies functioned during the 30 years war interesting.

A few things I can think of:

  • If everyone is taking care of themselves, you need to provide your soldiers with money, and you need to figure out how much money to give them. Normally, this doesn't need to be centrally planned because people can decide for themselves how much they need to work to get the money they need to survive, but presumably you don't want your soldiers taking other jobs.

  • If someone else is providing the supplies your soldiers need, then you need to give those someone-elses access to your soldiers. I think historically this was kind-of a thing that happened with a long train of merchants following an army, but I doubt military commanders want hordes of definitely-spies in their camps.

  • Central planning can be more efficient. Producing millions of identical MRE's is (presumably) more efficient than providing soldiers with a large selection of food and dealing with the waste when they don't like some of it. The obvious downside is that MRE's are allegedly-food that no one would buy if they had alternatives, but if you're focusing the output of your workforce on a war, trading off happiness for efficiency can be worth it.

  • You probably don't want your soldiers dealing with logistical issues, just as a matter of specialization. If you can have someone else figure out how to get allegedly-food MRE's to them, then they can just focus on fighting. I think you see something similar with colleges and certain kinds of jobs, where they provide housing, food, and some entertainment. But obviously the downside is that very few people want to live in dorms eating alleged-food, so you can only do this if people don't have any better options or are being forced to do it for some reason.

Something to consider is that similar things happen with companies too:

  • Almost all companies have specialists to pick offices and furniture, presumably for specialization and economy-of-scale reasons.

  • Most companies don't want random people walking through their offices. At small scales, they just accept the (time) cost of employees leaving to get food, and at large scales they typically provide food on-site.

If you look at wars during the Antiquity, barbarians would rush to combat in disorder. They would challenge each other to kill the most enemies to keep themselves motivated. And they were utterly decimated by the roman legion. Hierarchy replaces morale with discipline: centralised armies can push soldiers way beyond the point where they would give up and flee if they could. Therefore, trust is less an issue in centralised armies: each soldier can be assured that their neighbour will not leave their side at the worst moment. This in turn boosts the soldier's morale. Unorganised armies would rush to combat, but also break and flee easily, which made it easy for fast troops like cavalry to chase and slaughter them.

Also, strategy: sometimes, troops must be sacrificed to make a higher gain. Who would volunteer to be sacrificed?

The general rule is something like militaries fight to win the previous war.

However, technological and social changes cause tactics to change, and this changes how much central planning matters and how much more vs. less central planning is a help or hindrance.

So to me the interesting question is not why was WWII centrally planned (answer: people figured based on the Great War that's what would help them win) but is central planning being used efficiently to maximize outcomes across a complex multidimensional space?

Sometimes the answer is going to be that, say perhaps in the case of WWII, less central planning would have resulted in more deaths, and so the deaths due to central planning were an acceptable tradeoff.

Delegation of authority -- "management by objectives" -- is the newer style of command since World War II.  The lower-level commanders are given goals but are allowed to choose how to achieve them. This was only enabled by improved communication and control measures.

In Germany that would be Auftragstaktik which is older then WWII (the German Wikipedia gives 1866).

The idea behind it seem to date to the wars against Napoleon but could at first only be a applied to the higher leaders. To apply this idea to leaders lower in the hierarchy needed technological advances:

"It was not until the innovations in weapons technology from the late 1850s onwards, above all the introduction of the breechloading rifle and the resulting battlefield revolution (dissolution of the closed form in favor of a dispersed fighting style, introduction of the rifle squad instead of the company or even battalion column as the main fighting form of the infantry), that the lower troop leaders were forced, as it were, to take on more responsibility and initiative (not to be confused with acting on their own authority)."

Auftragstaktik in Vergangenheit, Gegenwart und Zukunft (translation by Deepl)

Having soldiers handle logistics for themselves existed for an extended period, but had major problems. In practice this often looked like soldiers foraging/looting for food, which can work in the short term but has major problems. Foraging parties are vulnerable to attacks, can provoke the populace against you, and eventually deplete easily available resources.

An army relying on foraging/looting could (and some did!) find itself unable to stay in one place for too long as a result of these dynamics, which would be awkward in a siege or similar (sure, you can go plunder the countryside around the castle, but you might run out of stuff to plunder before the guys inside the fort run out of their food stockpiles...). Similarly, if you're besieging the enemy but your guys won't be able to scavenge for food effectively once winter arrives, you might be forced to withdraw prematurely.

Why wouldn’t all these logistical details be simpler and cheaper in the usual ways if each soldier looked after himself mostly? 

Nope.  Even in peacetime, people do NOT look after themselves mostly.  They cooperate and compete in a system that takes care of most.  This peacetime system only works with sufficient cooperation, and that cooperation requires information (often in the form of prices, but a lot of additional prediction and data is used as well) to be relatively freely available.

In war, there is an organized agent (or set of agents, if you think of the enemy as decentralized as well) actively disrupting the cooperation, and using any available information to hurt you.   Central, top-down planning allows the knowledge to be kept secret for longer, because public knowledge is not necessary to the functioning of the system.

This reminds me of Cynefin, that breaks human situations in to domains. The complex domain is where decentralized seems most relevant. This is where perpetual novelty can be met with experimentation. Examples they give for how to operate in the complex domain, are:

The marines use these heuristics:
Keep Moving, Seek the High Ground, Stay in Touch  (a rif by someone in that community)

Napoleon used this heuristic:
March to the sound of the guns

Going further using the framework, logistical problems, although immense when be solved in the complicated domain, that is, with good practice and repeatable results can then be scaled.