I don't think contemporary theory has ignored this - see recent theories of density-dependent selection here: (article making the same point), (review). The fundamental issue you're hinging on is that absolute population growth (most effective exploitation of resources) is an ecological concept, not an evolutionary one, and population ecology theory is less well-known outside its field than population genetic theory.
As far as I can tell, density-dependent selection is an entirely different concept from what I'm trying to get at here, and operates entirely within the usual paradigm that says natural selection is always optimizing for relative fitness. Yes, the authors are trying to say, "We have to be careful to pay attention to the baseline that selection is relative to", but I think biologists were always implicitly careful to pay attention to varying baseline populations - which are usually understood to be species, and not ecological at all.
I'm trying to take a step back and say, look, we can't actually take it for granted that selection is optimizing for reproductive fitness relative to ANY baseline in the first place; it's an empirical observation external to the theory that "what reproduces, increases in prevalence" that evolution within sexual species seems to optimize for %-prevalence-within-the-species, rather than absolute size of descendants-cone.
Unfortunately you did nerdsnipe me with the 'biologists think' statement so I am forced to keep replying!
It's worth noting that the original derivations of natural selection do use absolute fitness - relative fitness is simply a reparameterization when you have constant N (source: any population genetics textbook). This was why I brought up density-dependent selection, as under that framework N (and s) is changing, and selection in those circumstances is more complicated.
In fact, even under typical models, relative fitness and absolute fitness show interesting relations. See this paper by Orr where alleles (which in this model only affect relative fitness by increasing absolute fitness) show diminishing returns on excess fecundity. The first paper I sent you also explicitly says [that absolute fitness is required under N-varying s or T-varying N] in the abstract.
I thought you were making a more subtle point about the additional demands of life history theory vs. the pure allele-eye view, which I agree is interesting. I hope I have convinced you that biologists are already doing fruitful work in this area. I don't understand the mesa-optimization arguments well enough to tell whether such an analogy is useful (to people who work in AI), but I do think it is true in at least a trivial sense.
To me your post feels like you are arguing against some pop science understanding of evolution instead of looking at what those biologists who use "evo math" actually belief in 2024.
Does natural selection, in general, really go by inclusive relative reproductive fitness?
Does sexual selection? This seems somewhat likelier.
Obviously there's a trivial sense in which the type of reproductive fitness that natural selection selects for, in general, is not relative. The coarsest denominator, the "bottom-line" aggregate replication rate of DNA-on-Earth, isn't capped as an absolute, and I imagine [although I could be wrong about this?] that the Anthropocene has rapidly increased it [even as "Evolution, in producing humans, may have entirely doomed DNA" in the long run].
Instead, local aggregate DNA replication rates - whether of the entire biosphere, of the clade Mustelidae, or of the ecosystem constituted by your backyard - are capped in practice by the availability of resources-in-the-environment to those organisms. The extent to which natural selection is modeling aspects of the gene's environment - prey species, predator species, resource-competing species, members of its own species - as adversaries, will of course in the most abstract theory of "what natural selection is" depend, in each local case, on how much each "adversarial" adaptation can marginally be expected to increase the allele's ultimate absolute descendants-cone.
I think biologists have come to think of natural selection, in general, as optimizing - even in theory - directly for inclusive relative fitness, because something like a mesa-optimization daemon which actually does do this even-in-theory, is operating in sexual species - a set-of-conditions for the gene/allele where all aspects of "maximize my descendants-cone" that are not "maximize my share of the species's descendants-cone [which species's replication rate is, from the gene's-eye, abstracted-away as invariant]" are functionally ignored by the main logical engine of mutation.
Biologists and those generally familiar with evo-bio math - I predict - will object to my suggestion that we reframe "inclusive relative reproductive fitness" as an optimization target of sexual selection specifically, on the grounds that it is trivial - of course, since relative fitness as conventionally taken-for-granted - the particular "selfish gene" that implicitly takes its main grounds of likely advancement, as victory in sexual competition with conspecifics - is a sexual-reproduction-confined optimization target, well, biologists already implicitly know not to model asexual cases as optimizing toward that conventionally-understood "relative fitness".
But I think treating this as a mere terminological nitpick, misses a potentially fruitful area of investigation for the question of why sexual reproduction took over at all, threatens to cloud our thinking on this topic in general, and also misses a potential invaluable second non-artificial data point for mesa-optimizer theory [ that is, we might get "natural selection -> sexual selection" AND "sexual selection -> human values", rather than just "natural selection -> human values" ].