Many mainstream philosophers have been defending Less Wrong-ian positions for decades before Overcoming Bias or Less Wrong existed.

When I read posts on Overcoming Bias (and sometimes also LW) discussing various human frailties and biases, especially those related to status and signaling, what often pops into my mind are observations by Friedrich Nietzsche. I've found that many of them represent typical OB insights, though expressed in a more poetic, caustic, and disorganized way. Now of course, there's a whole lot of nonsense in Nietzsche, and a frightful amount of nonsense in the subsequent philosophy inspired by him, but his insight about these matters is often first-class.