I agree with you about the tech-adjacent rationalist/EA community in the bay area (especially since around 2010). While that community originally coalesced around reason and evidence-based skepticism, those are uncontroversial ideas that've been around since the enlightenment.

Where the bay area rationalists went off the rails was in extrapolating far beyond those ideas to other things and then applying their new orthodoxy in rigidly dogmatic ways, eventually becoming 'a movement' with schisms, in-group/out-group policing, deference to influential members and ostracism for heterodox views.