I think it's much more valuable to have bad posts if those enable good posts to also exist, instead of just having no posts on the topic.

I disagree with this assumption. Discussions can have a net negative contribution to knowledge and understanding even if all their parts aren't uniformly negative. It seems to me that this is especially true on LW, since as long as there is no breakdown of discussion and everything looks nice and polite, people here tend to walk away believing that they've just participated in a sterling exercise in rationality and clear thinking, even if it's actually been a bad death spiral. That's my opinion, at least.