We had mutants in my world. People were not very nice about them, always wanted to corral them up or make them register so eeeeeeeveryone knew who they were. And then made stupid regulations making them essentially lower class citizens. Then there were Inhumans and there were all these cocoons after their leader sort of forced their transformation. There was this terrible person who tried to kidnap them and steal their powers. The Avengers weren't going to have any of that.