We don't have (or, really, want) to prevent the use of quasi-anonymous logins. All we need is to make life more miserable to trolls than they make it for everyone else. With enough frustration, trolls will gravitate towards places where they can sublimate their frustrations more easily and, hopefully, leave HN for those who really want to engage in civil conversation.

What do you gain from being rude?

And how does it feel when you get negative karma?

Where can I get one of these "advanced CS degrees" in black-hat trolling?

I do have a CS degree, but I must have missed those classes.