JK Rowling's views on trans people are also nearly the perfect demonstration that pg's "aggressive conformism" analysis is spot on. See, not too long ago those particular views were in fact something that was doing quite a bit of harm to trans people. They were being used to succesfully lobby for laws that did things like effectively deny trans women access to rape counselling and domestic violence services, and justify pretty awful campaigns of online harassment against any openly trans woman - not by JK Rowling, who seemed quite happy to just quietly hold her opinions, but by others. The reason you didn't hear much about this is because when these views actually had power, the loud, aggressive, well-connected warriors for social justice kind of supported them.
Now, it wasn't quite mandatory to hold these views back when I started following things about a decade, decade-and-a-half ago (though I remember Shit Reddit Says, the group trying to force Reddit to police its content based on their ideological demands, got quite close). What was mandatory was covering for them, shutting up about the laws they passed and the harm they did and pressuring everyone else to do so with allegations of misogyny. The arguments used to do this were quite reminiscent of present-day claims that "cancel culture" doesn't matter and people only object to it because they're bigots, now I think about it - supposedly the people pushing this didn't hold any power, and therefore the only reason for trans women to spend effort objecting to them rather than fighting non-feminist men, who by definition were the ones with real power, was because they had a misogynistic hatred of women. It was only when those views actually lost their power and relevance that the loud, aggressive, well-connected online activists switched from covering for them to demanding that everyone support beating up elderly lesbians for merely existing in public whilst holding transphobic views. (I am unfortunately not exaggerating, this actually happened - and yes, it was definitely the same people. pg's remark about "an exclamation point after a variable" is an extreme understatement.) This shift was quite recent too - maybe around 2016 or so?
There were of course actually non-conformist people with moral views that didn't just follow the crowd and various levels of aggressiveness who balked at this at the time. They just ended up being effectively irrelevant - too far from the status quo for its supporters, but so throughly and aggressively labeled as evil supporters of it by its organised, orthodox self-proclaimed challengers that few people seeking to challenge it would listen to the non-conformists.