It is actually kind of simple really. If you have fixed identity (or even psuedonyms that are tied to a "true name" a la Chaumian credentials) then filtering ou

It is actually kind of simple really. If you have fixed identity (or even psuedonyms that are tied to a "true name" a la Chaumian credentials) then filtering out bad behavior becomes easier. Users cannot create sock puppets, they get one chance to troll and then join the global killfile or get put a sufficient number of user killfiles as to have the same effect. If the identity was non-pseudonymous or the pseudonym systems supported cross-domain joins it would get even harder to troll since a trolling attempt at site A might get you added to user filters at sites B and C. The trolls would not go away, but no one would ever see them and this would have the same effect.