Yeah, that's pretty special. Personally as a cis nerd, I find the neurotypical obsession with gender roles pretty weird. I think we would be healthier if there were less of it, and like that we seem to be heading that way. But I don't think that makes everybody mentally ill.
Worth drawing a distinction between gender roles, which are mostly "socially constructed", and gender identity, which is someone's inherent sense of their gender (with a strong biological component).
Gender identity is an essential part of what makes us human. Some people have a stronger sense of it than others. To the extent that mental illness describes an actual objective thing, having a gender identity does not make someone mentally ill, because it doesn't by itself disrupt one's healthy functioning in society. It is when that gender identity is invalidated by others that it can affect people's mental health (just like calling someone a slur or insulting them can affect their mental health). It is still not an illness, though.
