"I would find it strange for anyone who's seriously interested in AI to have never heard of Yudkowsky or Scott Alexander or the Rationalist movement."

But, it would be pretty surprising for most folks to have gone to the same parties, and hung out on the same obscure forum (I don't mean HN, more obscure than that), and received investment from the same investors and shared the same pool of researchers and employees, which is the situation we have with Anthropic, OpenAI, and (maybe to a lesser degree) Deepmind.

The American AI industry is particularly insular and tied up with some particularly unusual people. We've all heard of Yudkowsky, but we (at least I) haven't been to the same parties.