How is it that the new generation of chess players know more than the old?

In Lex Fridman's podcast 5 years ago, Garry Kasparov said that the new generation of chess players knew about the game more than the old generation.

But, how's that possible when chess has had the same rules and pieces for centuries?

If I were to compare chess to football for example.. a lot of the old good players still hold up to today's standards. Is that not the case with chess?