Yea, sure, the genre is the problem. Certainly not the fact that 90% of all the modern anime just feels like you have a ready preset of character types and reactions, couple stereotypes about Japan and world building blocks, then you just mix and match those together.

There are plenty of good isekai anime, the genre rarely defines whether the show is good or not. It's just that if your main character is a regurgitated Mary Sue (or a male version, doesn't really matter), your world is a dead standard LitRPG teen creation and supporting characters only exist for the sake of posing as a harem, maybe the show being isekai is not the problem?