The reason there are no polymaths in this day and age like there were hundreds of years ago is - rather straightforward, I think:

In DaVinci's time for example, it was still possible to know (almost) everything there was to know about anything. Physics, Biology - the whole of natural sciences was already diverse, but the amount of information was not even one percentile of what it is today.

Try learning the actual data and scientific theories even in only one discipline - physics for example. Impossible.

Of course there are still people with diverse interests, self-discipline, time on their hands and who take pleasure in learning - and they can have an above-normal knowledge of various things.

But a modern DaVinci... impossible. I bet there is not one person on this planet who knows as much about biology as the most knowledgeable biologists do AND as much about physics as the most knowledgeable physicists do. Hell, with the subdivisions of these sciences, I bet there isn't one biologist who isn't exclusively a microbiologist, or zoologist etc who knows as much about microbiology, zoology, population genetics etc as people in those fields do.