Re. "this is the best time to be a polymath". I was noticing something like that. For a while it became impossible to know or do "science" ("philosophy", was it?) as a whole. Too broad, too deep. That was not the end of the polymath but it was the end of truly broad expertise in one individual. Then the net in general made so much info available painlessly. (Much faster to dig deep on a narrow issue and switch issues - than say, even with a large academic library.) So that now, it's still not possible to master the forefront of tech or science on a very broad front, but it is possible to dig deep as needed to address this or that problem in the pursuit of what is now just about always a multidisciplinary project.

With the very present danger that many feel that a couple youtube videos is as deep as they ever need to go.

Being able to gauge how deep and broad you have to go for each difficulty you encounter has become an important skill. But polymath seems very possible.