The whole is greater than the sum of the parts. I think that any hardcore specialist will be missing out somewhat on the synergy that knowledge of the various parts of the universe provides. But given our educational advancements we're much more well rounded in terms of education than people a century ago. So in that sense we're all polymaths. And having a general understanding of a variety of topics can still produce some synergy towards increased understanding of the universe or any specific topic.

Our intellectual capabilities haven't changed but the amount of knowledge we know amasses. So eventually, which is happening now, we'll reach a point where it is no longer possible to be at the head of multiple (at least scientific) fields because there is too much to remember. Part of the reason for this is because people have specialized terminology and field specific nuances that must be learned ( as opposed to having concepts described in common language).

Art is an exception, because it does not advance quantitatively like science. So we should still be able to excel in specialized knowledge and be able to artistically express ourselves. This is also why, as the article mentions, lots of people write. It's a form of expression. Anyone can write as long as they have a good idea, and anyone can paint or compose since the difficulty in doing these things has remained constant.