I was interested by the "Where's Beethoven" graph, and went to read the original article (which is better, and doesn't actually agree with the idea that it's measuring a decline of genius). I'm kind of astonished that neither article considers the possibility that the effect they're seeing is that opportunity for acclaim doesn't scale with population.
The absolute population has more than quadrupled since 1901. If I understand the data being used here, the "effective population" has increased over 100 fold in that time period. Yet the number of people receiving Nobel Prizes in any given field each year hasn't appreciably increased. And we would likely perceive the Nobel as less prestigious if they awarded 4 times as many a year -- certainly if they awarded 100 times as many. The same can be said of awards in art, music, and other fields.
Awards are obviously not the only way of measuring prestige. But the same could be said of coverage in prestigious journals, or by renowned critics. Nobody would reasonably expect there to be 100 times as many top-tier literary journals in 2021 as in 1901. It almost seems like a contradiction in terms, doesn't it?
I think a limiting factor here is that acclaim is a matter of mass agreement. A single person can only watch so many films, listen to so many songs, read about so many scientific accomplishments in a day. A film critic in 2021 is probably not watching that many more movies a week than their counterpart in 1960. And it's not like movies are load-balanced between critics.