Thanks for writing this. It's true that LW has a record of being bad at talking about gender issues; this is a problem that has been recognized and commented on in the past. The standard response seems to have been to avoid gender issues whenever possible, which is unfortunate but maybe better than the alternative. But I would still like to comment on some of the specific things you brought up:
assertions that understanding anyone of the other gender is like trying to understand an alien, for example.
I think I know the post you're referring to, I didn't read this as sexist, and I don't think that indicates a male-techy failure mode on my part about sexism. Some men are just really, really bad at understanding women (and maybe commit the typical mind fallacy when they try to understand men, and maybe just don't know anyone who doesn't fall into one of those categories), and I don't think they should be penalized for being honest about this.
gender essentialist
I haven't seen too much of this. Edit: Found some more.
women-are-objects-not-people-like-us crap
Where? Edit: Found some of this too.
I think it has fallen very squarely into the "nothing more than sexism, the especially virulent type espoused by male techies who sincerely believe that they are too smart to be sexists" cognitive failure mode.
This is a somewhat dangerous weapon to wield. It is very easy to classify any attempt to counter this argument as falling into the failure mode you describe; please don't use this as a fully general counterargument.
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