The problem with this "moral" expectation you want to put Facebook or any company in a social space under is that it's self-contradictory and hypocritical. I don't know any reasonable person who would want the phone company, a very centralized system, to play the role of morality police over who can use the telephone and who can't. This "Centralization = ownership of everyone's actions" view just imposes the burden of a mass of cultural expectations on companies that never agreed to any of it.