Yeah, ok, perhaps the 'dear' comment is a case in point - is that the sort of thing people mean?
Tbh I usually see that sort of comment aimed at people who have repeatedly argued black is white, so to speak. It's not ideal to get that exasperated and I suppose it is condescending (and a bit sexist, unfortunately...) - but wasn't the 'dear' aimed at the poster who kept on and on denying that taking your husband's name is rooted in patriarchal traditions? I mean really!?
Yes, posters who are wilfully ignorant will get patronised. But that's the case on any forum. Don't see why feminists should be held to sterner standards...
On the transgender issue, as far as I can see, the gender critical feminists on MN have categoically destroyed the argument for letting transwomen into female spaces time and time again. They have dismantled, completely, every counter argument. No one has successfully won an argument that transwomen should enter women's spaces. So I forgive any exasperation or condescension on those grounds.