Lots would play by the rules and provide genuine criticisms during peer-review (which will lead to the alteration of the content of course), along with criticisms post publication.
Do you have any experience with peer review? In the most functional fields, peer review does a good job of assessing what is valuable, but provides no improvement in quality. In most fields it demands edits to make things worse.
I have experience with peer review, on both ends, and I strongly disagree with you.* What has your experience in peer review been like? In what field?
(*) Peer review can indeed be quite bad, and I had bad peer review before. But this has been an exception rather than the rule for my papers. I understand that I introduce selection bias by only looking at my papers.
I feel that a lot of what's in LW (written by Eliezer or others) should be in mainstream academia. Not necessarily the most controversial views (the insistence on the MW hypothesis, cryonics, the FAI ...), but a lot of the work on overcoming biases should be there, be criticized there and be improved there.
For example, a few debiasing methods and a more formal explanation of LW's peculiar solution to free will (and more, these are only examples).
I don't really get why LW's content isn't in mainstream academia to be honest.
I get that peer review is not the best (far from it, although it's still the best we have, and post-publication peer-review is also improving, see PubPeer), that some would too readily dismiss LW's content, but not all. Lots would play by the rules and provide genuine criticisms during peer-review (which will lead to the alteration of the content of course), along with criticisms post publication. This is in my opinion something that has to happen.
LW, Eliezer, etc, can't stay on the "crank" level, not playing by the rules, publishing books and no papers. Blogs are indeed faster and reach a bigger amount of people, but I'm not arguing for only publishing in academia. Blogs can (and should) continue.
Tell me what you think, as I seem to have missed something with this topic.