surely they're talking about the opening only, where the best moves have been analyzed to death. once you're in the middle game and it's a position that's new, you play the best moves.
Hans' explanation made sense, even if he was wrong in his first interview and it came off weird.
I think that’s what Magnus is saying is that if you play by the book you go from opening to end game without much creativity or challenge.
So, the top “creative” players will try to go off script to make their top “book smart” opponents have to think on the fly.
But even in mid-game, it might mean that if you know that your opponent prefers open / tactical positions, for example, you try to force a closed position, even if it may be slightly suboptimal.