Or that women tend to be calibrated differently in determining what level of warmth/coldness should be interpreted as hostility.

I think that's certainly part of it - they have different priors for the relationship of intent and associated comments. Theirs is probably more common in general.

To sketch another stereotype, analytical/smart/nerdy people will tend to be more cold and robotic, treating more as machines than as people, and having poor empathic skills.

To put it differently, nerdy people have different habitual goals in speech. They're trying to communicate facts, not interact/handle/manipulate people. They may have empathic skills, but they're not always applying them.

I wonder how much of the perceived distinction between male/female styles correlates to time spent in ideologically heterogeneous communities. If you're only used to discussions with an in group, the out group will feel very jarring and hostile. This is probably more of an issue for progressive posters, as libertarians rarely have the choice to be in an ideologically heterogeneous community. Also, I suppose anyone with any religious impulse would find the atmosphere rather hostile as well.

And almost all emotional queues are lost online. For people who habitually make emotional evaluation a prime part of their mental focus in a discussion, it must be rather disorienting, while nerds will be perfectly comfortable and at home. Nerds were made for the net, the net was made for nerds.