I'm also pretty sure that there's an actual category of discourse that involves men explaining things in a tone of certitude but from a position of ignorance.

People certainly explain things in a tone of certitude from positions of ignorance, like, all the time. And I find it plausible that this is more common among men since exuding competence and knowledge tends to be more important for male status and men seem to be more concerned with "winning" arguments than women. But I don't see any good reason to make the phenomenon about the relationship between genders. I'm male. My male friends "mansplain" to me all the time. I "mansplain" to them. But most of my friends are highly intelligent, opinionated women-- and all of them "mansplain" to me too.

It's a bad epistemic habit and often disrespectful. It's talking to seem impressive instead of talking to learn or share. It's important for rationalists to avoid it. But I think it's really absurd to suggest it is something only men do-- to the point of referring to it as "mansplaining". Especially since the issues on which -in my experience- women most often talk with certitude from a place of ignorance is gender politics, particularly regarding the experiences and motivations of men.