Well TBF, AAA still does have a bunch of different genres. All the different sports games, shooters, linear action/adventure, open world action/adventure, RPG, a plethora of different types of fighting games, etc. The problem is the viable mold has been cast and set to where even all of those have been done for generations now.
However, we could even apply the same logic to a lot of Indie stuff which mostly boils down to either side scrollers with some form of combat and platforming, or some variant of isometric strategy games. The point is there’s literally more than enough variety to pique someone’s interest in something, but also that people’s tolerance for fatigue will vary.