Anand isn't really talking about strategy here, he's just talking about choice of opening. Players with narrow opening repertoires, like Fischer, have always been easier to prepare for than players who play a wide variety of openings.

As far as actual changes to strategy, the most obvious one is that computers tend to value material more highly than humans. So a computer will take a risky pawn if it looks sound, while a human will see that taking the pawn is very complicated and prefer a simpler move.

(1) Online game databases have made it easier for players to track developments in opening theory and prepare to play specific opponents

(2) Chess engines add to this be used to search for antidotes to complicated opening systems

(3) Young players have greater access to high-quality sparring partners - either engines or fellow humans on online servers.

This has lead to the best players becoming younger, and players playing more varied and less 'sharp' openings.