It requires manual moderation. Companies like Facebook, Google, and co. have spent much effort telling you that's impossible. In fact, that is a type of half-truth that is a lie. The full truth is that it's impossible _at their scale_.

Their business models require little to no human moderation, because it simply doesn't scale (for their business to stay profitable).

Personally, my feeling is that if you can't take care of your product, you should go out of business.