That works when you're dealing with something the scale of HN and have the resources to hire dang. At the scale of Facebook or Twitter, though? The sort of moderation you're describing is just impossible.
I moderate a largish, active Facebook group on a controversial topic (5k members, 3-5 posts a day). I spend about 10 minutes per day on this on average. But the fact that I care about the topic, that I can directly ask people to not to engage in shit and that people want to have a decent are basically what makes things much easier.
So it's possible on Facebook. It's just not possible for just Facebook. Reddit seems a better model for community at scale but somehow I haven't jumped into that.
