Controversial take, but please believe I'm making it in good faith:
Obviously this is bad, but I hope people realise that these kinds of attitudes are still incredibly pervasive, sometimes where you would least expect them.
You'll sometimes see people who think of themselves as feminists or progressive, have a superficial(!!!) understanding of identity politics, treat abstract even stereotypical ideas about gender as if they're real things, and reinforce essentialist and binary ideas about gender. They'll shout down those who don't have the same identity based 'lived experiences' and claim they have no right to speak on certain topics.
It ranges from the banal: someone claiming the only reason someone could possibly be criticial of the Barbie movie, is because they're not a woman.
To the outright toxic: progressive women who were assigned female at birth (cis/not trans) who are transphobic against trans women because they're not 'real women' because they haven't had the same 'lived experiences' and therefore don't have the right identity to speak on 'real' women's issues or become part of the women's movement. Of course, trans women aren't cis women, but that doesn't mean both don't have enough in common to both be considered women. Nature's messy.
I suspect this partly explains what happens with people like JK Rowling, who think of themselves as feminists but in practice are increasingly(?) sliding into essentialist, regressive and right wing ideas about what it means to be a woman, thereby helping to foster division among people who share a common cause and inadvertently undermining the women's movement.
More generally, binary essentialist thinking can be incredibly divisive and undermine stuff like class consciousness. I may have been born with a penis and think of myself as a boring man, but that doesn't mean I have nothing in common with a black trans sex worker. We're both getting fucked by the Elon Musk's of this world.
This comment was overly long and stream of thought. I go sleep now.
