Well I see part of the potential being a working reward system, which however seems to be too complicated for many people as they're longing after a flat reward system. It would probably be a flat zero then.

Also I do not really see how moderators would help the platform. At that point we'd really see the "you're not allowed to criticize"-phenomenon you seem to be worried about. Of course now high SP users can flag posts/users to below zero rewards etc. but moderators would have stronger power than that and I see no point in it.