Fischer was able to think outside the box more than any other player in history.I think the only reason a lot of the young straight shooters can match up well in 1p with players like Scott and Tony today is because of the wealth of knowledge available at the click of a mouse. They can look up things that used to take players years to figure out. It's a lot like chess. Let's say you bring back Bobby Fischer, maybe the best player that ever lived. He might struggle today even against top 100 players because they have access to computer engines, more game databases, and many new theories since the 70s.
Magnus, Kasparov, Kram, all would face big problems playing Fischer.
Let's not even talk about if they played Fischer Random how badly everyone would do against him.