I think what @flyingbuttress43 is saying (and correct me if I am wrong) is not blaming 3rd wave feminists for what has gone on regarding trans, but pointing out that what they have done has not helped to stop it.
It's the moral difference between stealing something yourself, and seeing the theft and not telling the shopkeeper.
There are many reasons why well-intentioned young women have fallen into the performative idiocy of wearing she/her name badges, many related to female socialisation, the ongoing male domination of society, the desire to avoid standing out from the crowd and making yourself a target. In that sense it's not their fault, but I wish they'd wake up and smell the roses.
One of my DC is like this. Intelligent, good-hearted and yet, despite my best efforts, completely clueless about the wider implications of the trans movement. The propaganda these young people have been fed is widespread, clever, and deeply manipulative (be kind, it's about human rights, women's rights and trans rights are the same thing, right side of history, prevent trans suicides, it's like gay rights). It's sidetracked many young people from more useful forms of political action. I just wish they'd fully engage their critical faculties, but that requires awareness, courage, independent thought and a degree of humility.
But Mum is a dinosaur who hates trans people, so I won't listen to her.