I agree with your point, especially "Educated feminists know that poor mental health for men only hurt their situation," but it's really frustrating to be told "This isn't real feminism" when the harm misandrists do is very real. It feels like there's a double standard - when men talk about the problems misguided or undereducated feminists cause, they're told to be specific in their language and not to generalize. In the same breath, people who at minimum appropriate the feminist banner do a lot of generalization about men. You see it all over this site and in pop feminist circles, and being told "Well you can't criticize feminism just because some people do it badly" leads to a lot of resentment.

It also doesn't feel fair to say "Well they were being vague". A lot of the harm perpetuated by patriarchy, misandry and other elements in society is amorphous. A lot of people don't have an acute moment of pain - they internalize things over time, or have lots of small incidents. Getting hurt and being told to man up, being told that men don't belong in queer spaces, or that all men are pigs.