Culturally, it is much easier to block an annoying person and delete a poorly written post on facebook than ban him on Less Wrong. As a general rule, people like being kings in their own small kingdoms instead of being merely citizens in a larger country, that's why people move to personal blogs. On Less Wrong you are a citizen, you cannot set your rules and impose them onto others and expect that others will simply agree to them.
Eliezer commented on FB about a post Announcing GoodAI (by Marek Rosa GoodAIs CEO). I think this deserves some discussion as it has a quite effective approach to harness the crowd to improve the AI: