Maybe it's changed in the past five years, but I don't recall being treated disrespectfully when I was active on /r/mk and deskthority (can't speak for geekhack, and I admittedly wasn't very active on deskthority).
As what switches/layouts/keycaps/etc. folks like are highly subjective and sometimes polarizing, I would often see people espousing opinion as fact. But no one treated me rudely even when I asked dumb questions in their daily discussion/advice threads.
I agree that much of the community consists of essentially bragging to other people about your own keyboards. But I saw even braggarts showing up in newbie threads to try and help other people get into the hobby.
Edit: I will add though, I tend to lurk for a while and gather knowledge before I even ask a newbie question. And I probably fit better with the kind of boys club tech bro culture that you're implying is prevalent (although I can't say I noticed this all too much).