I think the "must think whatever I'm told to think to be a good person, I'm not a mean old bigot!" effect is extremely powerful.
People just know that what they've been told must be true (trans people are the most marginalised and oppressed minority in the world, no one would ever pretend to be trans for an ulterior motive, you can just "be" the opposite sex in some indefinable way that no one is allowed to question) - because to dare to have any questions would mean they're a bigot or "right-wing" and their number 1 priority is to defend themselves from that accusation and cling to the moral high ground.
That doesn't allow enough mental space to consider that all these dogmas have come from the same lobby that you are now being asked to make special allowances for and give priority to. It doesn't allow the thought processes that allow you to think "but this doesn't really make sense". If you catch yourself thinking of a TW as a man, that's a you problem and you must try harder. Only "inclusiveness" and "diversity" matters and you can conveniently block out that there are multiple situations in society where there are biological categories for safety and fairness and people are excluded from them all the time, on the basis of not belonging to them.
Posters such as *Onetimeonlyftw *cannot successfully argue their points on the basis of reason, logic or clarity, They have been asked multiple times to explain how a man can be a woman "socially", or how it's not OK to identify into other protected categories, either, or how you can tell a TW from an impostor when self-ID is the only evidence someone is trans. But they cling doggedly to their beliefs, not because they make sense, but, IMO, because the idea that they would be a "bad person" or "not a proper (i.e. man-prioritising) feminist" if they didn't toe the line is too strong.
Ultimately it's a selfish (but understandable) motive, needing to jostle up the greasy pole of righteousness by denouncing others and proclaiming dogma. And that need is being brilliantly exploited by a very harmful movement whose claims have no evidence behind them.