Weighing back in here, I will clarify my comment which the comment you quote was based on, that my OH had this precise thought ("self-important pompous fools") when he came across this site initially. The content of the sequences he found trivial. He generally finds it easy to be rational, and didn't see the point of getting a community together to learn how to be more rational. In fact, it's a large (reverse) inferential distance for him just to understand that some people find figuring these ideas out actually non-trivial (and yet still care about them). He doesn't understand how people can compartmentalise their minds at all.

Very few people sort themselves in bands according to "rationality", and my OH takes part in just regular discussions with regular smart people, except he's better at correcting wrong arguments than most. "Some people being unfixably wrong about things" is just a part of life for him, and without ideas like transhumanism to motivate you, it's quite hard to bring yourself to care about how wrong the rest of the world is - just being right yourself is sufficient.

Implied in your so called 'question' is the statement that any online community that you know of (I shouldn't assume you know of 0 other communities, right?), you deemed less rational than lesswrong. I would say lesswrong is substantially less rational than average, i.e. if you pick a community at random, it is typically more rational than lesswrong. You can choose any place better than average - physicsforums, gamedev.net, stackexchange, arstechnica observatory, and so on, those are all more rational than LW. But of course, implied in your question is that you won't accept this answer. The LW is rather interested in AI, and the talk about AI here is significantly less rational than talk of almost any technical topic in almost any community of people with technical interest. You would have to go to some alternative energy forums or ufo or conspiracy theorist place to find a match in terms of irrationality of the discussion of the topics of interest.

You would have no problem what so ever finding and joining a more rational place, if you were looking for one. That is why your 'question' is in fact almost purely rhetorical (or you are looking for a place that is more 'foo' than lesswrong, where you use word 'rationality' in place of 'foo').