1. Why do so many good things have horizontal transmission structures?
Memetic horizontal transmission that is mediated by human normative judgement routes around this filter... in some manner. Maybe they are slightly hacking your perceptions of goodness? Also, maybe these filters improve things some.
Far be it from me to claim that modern horizontally transmitted cultural ideas are bad. I would never...
However... between 1800 and 1950 it would have seemed to little children that smoking was terrible, but then if their peers smoke, smoking starts to seem like a way to minimize the disgust, and shortly it begins to seem pretty great, and this becomes the widely shared common wisdom among adults in a society with very high smoking rates. With smoking there was careful centralized analysis, with data collection, and peer review, and careful reasoning about causal models. Eventually we figured out: nope. I can tell you a story about how my mom stopped smoking when I was a kid, and then my brother and I copied her by not starting.
I would argue that "good careful reasoning" is the exception that proves the rule in some sense, because lots of so-called Official Science(!) is pretty shit (parts of tongues that taste different things? wtf? is it all just gossip? when did academia give up on "nullius in verba"?) and the good stuff tends to be invented by a TINY group of people and spreads via *baroquely* cautious transmission patterns.
2. The conclusion seems severe and counterintuitive...
In memetics, this is what trusted priests or scholars are an attempted patch on, I think? I'm sorry. I don't know any good news here.
Biologically, viruses prey on bacteria. Both are made of nucleic acid but some nucleic acid content is aligned with the protein inside the membrane... and some isn't. The "better" viruses are prophages (integrating with the genome and conferring useful phenotypes)... but often they go lytic eventually... and then the infected bacteria's daughter's daughter's daugher's daughters have a regret-worthy outcome.
If people have lots of unprotected sex, a venereal disease eventually finds the niche created by that aggregate behavior. If people fly around in airplanes while sneezing on each other, an aerosolized disease eventually finds that niche. If people drink from a river downstream of where other people poop in the river (especially if some of the the drinkers then travel back upstream), cholera happens. When you feed cows to cows, prions grow exponentially and eventually there's mad cow disease. If elementary school teachers who have never been outside of the school system teach school children who become teachers who teach children who become teachers... You will end up with the curricular equivalent of bovine spongiform encephalopathy.
How long until twitter collapses? Has twitter died already? I'm sorry. The circle of life is best when it circles very VERY widely. Gotta turn it to mulch. Then have fungus eat it. Then let the fungus dry out in direct sun for two years. Then use it CAREFULLY. It makes me sad, but I think it is true. Do not recycle "vital" things!
3. What about The Moral Economy by Samuel Bowles?
I have not read the book you cite. I want to defy the data. I would suggest that high social capital causes prosperity and enables trusted third party mediation, then, because people socially trust the third party mediators, it enables quick interactions based on shared traditions (that affirm trust and that often rely on deeper "trust rails" go back decades or often centuries (often literally to shared ancestors)). This could cause correlations in single temporal snapshots of data. Massaging such snapshots in modern academic writing, people have an incentive to tell happy lies in public like "prosperity causes social capital". The traditional theories here (and the long term economic demography), suggest to me that great wealth is generally squandered by the fourth generation, so the data collection I'd like to see would span 6 generations over various cultural cross-sections, or else it would span maybe like 10 generations (to hopefully see two full cycles)? I would love to be wrong about this, but my priors are strong enough that I want to see very very rigorous data collection methods as part of the presentation of why my priors here should be weakened. Maybe writing a rigorous book review of the contents of The Moral Economy would be virtuous!
If there was a key countervailing idea here, for me it is "acceleration itself". Progress. The increase in the number of humans, and per capita energy use, and humane culture-making activities. Old functional things are being copied and the "oomph" has not burned out... yet! :-)
0. Where did this theory come from and is it horizontal or vertical itself?
I'm going to assume you asked this, and answer it! I invented the theory, basically.
The geminating idea is: Dawkins is just wrong. He used to go around constantly dunking on TRADITIONAL religion about how it was a virus, and he was just... wrong. Many many many generations of shared co-evolution often tames parasites by aligning them deeply with more "metabolic" vertical replicators. Mitochondria are tamed bacterial parasites. The V(D)J combinatorial immune system is a tamed viral parasite. Endosymbiosis is a thing, but it works in a certain way.
Tiny fast evolving things (like cults) are sources of novelty, and larger slower things (like 1000 year old civilizations with old co-evolved religions) must tame them, or be devoured. Novel horizontal culture is often pretty bad. I have extended this theory in various conversational domains going back maybe 15 years to before the launch of Overcoming Bias but it always seemed gauche (and inconsistent with the theory itself) to bring it up ONLINE in a community deeply built around "the rejection of the supernatural mumbo-jumbo of one's parents".
I have talked about the importance of vertically transmitted ideas with my parents (who are themselves second generation atraditionalists), and they roll their eyes, but are happy enough to tolerate my antics when I "larp" "filial piety". In the meantime, filial piety occurs in many religions. The Abrahamic injunction is obvious. If Confucianism has ONE PUNCH, that punch is arguably "filial piety". I have purposefully not talked about horizontal meme transmission where Google can see, but if that goal is to fail at horizontal at this particular historical junction during a horizontally transmitted global plague then I guess I'm ok with it? Naturally it would be better if my children could teach the theory "as taught by their mother" (me), but they do not exist (yet?), and so they can't.
(I would not strongly object if you deleted this post before it can be seen by Google and generally become less of a vertical meme and more of a horizontal meme... Evangelism just seems mildly evil to me, but I'm not evangelical about evangelism being bad... because that would kinda defeat the point? My interest here is mostly... credit assignment I guess? I'm a HUGE fan of thinking about The Credit Assignment Problem. If I have done wrongly, or well, then it seems generally proper that I be credited as having done wrongly or well. Similarly for you. Similarly for all choice-making beings.)