The idea that population numbers are all it takes is so stupid. Mozart is not just one guy who was really good at writing music. I mean, obviously, he literally was, but he only existed and wrote what he did in the way he did because of not only his own "genius" but also the circumstances he was raised in, his education, the musical traditions that he drew from, the fact that he was wealthy and had time... Etc etc.
Adding more people living in poverty, with poor education, no connection to musical or artistic tradition, and no time... Will not add more Mozarts.
"I am, somehow, less interested in the weight and convolutions of Einstein's brain than in the near certainty that people of equal talent have lived and died in cotton fields and sweatshops"
Most of the super famous classical composers were born with in 90 years of each other. On one hand thay were brilliant musicians, on the other hand It was also this thing that was happening right then.
I'm fairly certain if the circumstances were different we still have a bunch of people doing the same work.
Those composers are famous because they were pioneers in the development of music and their work has been used to educate musicians in virtually all countries during the last century. There are composers creating similarly valuable music today, sometimes working in cinema or video games, and composers doing pioneering work, usually in experimental music. They aren't as famous because their work isn't being used worldwide to educate musicians, but they might be by 2123, provided society hasn't collapsed.
That's part of what I'm getting at. The musical culture at the time arose through the work of many, many composers, and through the listeners who talked about it etc. Cultural development is complex and requires much more than just a handful of geniuses.