Identity can prevent abuse if it can be used as an effective way to keep the trolls out. In the real world if you know behaving badly can get you permanently ba

Identity can prevent abuse if it can be used as an effective way to keep the trolls out. In the real world if you know behaving badly can get you permanently banned from a place you'd like to have access to, that keeps you in check. Similarly if it was possible for service providers to effectively penalize (from suspension to permanent banning) abusers in a way that they can't easily circumvent (ie create a new account), that'll be effective.