I see people here who seem seriously interested in forming a more accurate view of the world -- but at the same time, living in a society that has vast powerful, influential, and super-high-status official intellectual institutions that deal with all imaginable topics, they show little or no interest in the question of what systematic biases and perverse incentives might be influencing their output.

I don't get that impression. The problems of biases and perverse incentives pervading academia seem to be common knowledge around here. We might not have systematically reliable methods for judging the credibility of any given academic publication but that doesn't imply total ignorance (merely a lack of rationalist superpowers).

But then what exactly makes LW useful or worthwhile in any way? Are the elite universities so marginalized and powerless that they need help from a blog run by amateurs to spread the word about their output?

That question sounds weird next to the preceding paragraph. Those perverse incentives mentioned earlier aren't exactly incentives to spread well-established scientific knowledge outside academic circles. The universities need help, not due to lack of power and status but due to lack of effort.