If there's any problem with MN's discussion of trans issues, it's that it gives a false impression of how open the discussion is. Whenever I'm on here, I see transactivists' claims being debated, agendas being questioned, and ideology being challenged (especially ideology which is elsewhere presented as fact).
It's not like this everywhere else. I don't just mean within transactivist circles: please, join an intersectional feminist group, or the Labour party, or try to leave a comment on a Guardian article, and see how tightly controlled the discussion is, to the point that there can be no discussion at all. You need to understand that the condition of talking about trans issues in almost every other setting right now is that you must subscribe fully to the TRANS WOMEN ARE WOMEN mantra, treating that statement as factual, incontrovertible truth, and that any hint of a misgiving you express will be, by definition, transphobic.
Many of the trans-positive, tolerance-positive comments on this thread would be deemed transphobic. No: you can't say you support the rights of trans women, but believe they shouldn't be in women's sport. Trans women ARE women! You can't say that you approve of self-ID but understand that there should be a few commonsense exclusions, e.g. women's refuges. Trans women ARE women! You can't project fears about male violence and male fetishes onto trans women. Trans women are NOT men. They have NEVER been men. They were assigned male at birth, but despite their physical form and socialisation they ARE and ALWAYS HAVE BEEN women.
There is no discussion permitted, which should be the first sign that this is an ideology which should be challenged very rigorously. And thank fuck for Mumsnet allowing this. For all that transactivists try to position themselves alongside historic civil rights causes, the movement increasingly has more in common with something like McCarthyism: an oppressive ideology gains a disproportionate amount of influence and swiftly entrenches itself, fucking up people's rights and limiting people's ability to express any sort of dissent/concern without being pilloried (or sacked, suspended, blacklisted, harassed).