To test that theory consider something unrelated like fine arts. Surely a ten million person city has more people with job title "artist" than a million person city, probably ten times as much. For the sake of argument say that when the western world measured populations in many tens of millions we got a legendary level playwright every millenia. Now that world culture has a hundred times the participants, we should have a legendary level playwright appear every decade or so. Just not seeing it. We have good playwrights, sure, but not legendary level every decade.

The upper end of mental scales, IQ or whatever, does not seem to follow the usual statistics for QA/QC of machine screw production or whatever simple industrial theory. On a purely numerical basis the world wide English Literature academic community should have maybe ten Shakespeare level professors active right now. If we do have those people, they don't have the job title "English literature professor". So where are they?

Part of the problem is "shoulders of giants". Perhaps I personally could have invented the calculus, but Newton beat me to it, so I'll never amount to much there. Under that theory unless we lose information as a culture, eventually academia will become perfectly sterile and actual advance will cease, although we can trust numerical metrics will increase forever into perpetuity as they always do unless confronted with reality, which in the case of that metric, is impossible.