The most dangerous religious fundamentalisms lead people to do things such as blowing up buildings, committing mass murders, jailing and torturing people for apostasy, and throwing acid in the faces of schoolchildren. This occurs both when dangerous religious fundamentalists occupy positions of formal political power (governments), and when they do not (terrorist groups, militias, abortion-clinic bombers).

Arguably, these kinds of acts follow a normal distribution (where acts of extreme altruism are on the opposite tail), so if Less Wrong had much larger numbers we should expect to observe these kind of things. Do you really think if Less Wrong had over 1 billion members (like Catholic Church) we wouldn't have members that commit violent acts (such as assassinating AI researchers not using FAI safeguards)? If anything, I would expect there to be greater variance of good and bad acts among Less Wrongers since they are explicitly trained not to compartmentalize.