I couldn't believe my eyes seeing this advice to teach young boys to hit girls so as to restore the boys' self esteem and pride.
This is the kind of toxic belief that shouldn't be allowed to proliferate here and yet is embraced with open arms by other users.
That boys can only regain their pride and self esteem by hitting girls leads directly to more violence against women and girls.
I do not disagree with this comment in any way.
But this is a very different comment than your OP.
If your OP had talked about "teaching violence supports patriarchy" I wouldn't be here discussing this.
"This kid should hit back" is not an overtly sexist position. It is a position that supports patriarchy, for sure, by reinforcing violence culture which advantages men in individual conflicts and harms their growth and development.
"This kid should hit back; it's not like they're a grown man and woman" is, IMO, a position of "it's not like they're physically mismatched". Not one of "it's okay/encouraged because of their genders".
I'm sorry that people on Lemmy continue to do stupid shit that enables and supports patriarchy. That is certainly a form of systemic sexism.
I still don't think this is a particularly good example of "Lemmy has a sexism problem".