Part of it depends on content. If you're a real community, then having people sign up for commenting and rating comments is a good solution. It helps promote good content and the requirement to sign up keeps the community free of a lot of hit and run commenter who might often degrade the experience.
If you're a news site, then most of your content is from hit and runs (hits and runs?). You don't have people hanging around your site all day, waiting to post on the next story. You have Drudgereport linking to you and then a flood of mouth-breathers leaving a quick comment about "libtards" or "republicraps" or a quote from some religious text and so on. In these communities, the discussion will never be lifted up and no voting system will work, because nobody is invested in it. Further, if you require a sign-up, nobody is going to bother.
Then, there are blogs. Sometimes you may want people to have to sign up but in other cases, you might need or want to just let anyone freely comment without any hurdles. Nobody wants to go through a signup process if they're only going to see your blog once or twice in their life (when linked to from HN or elsewhere, for example). It's hard to choose the right path, here.
I think much of the answer comes down to two things;
1) Human moderation - both by the community itself and designated moderators - is very valuable. 2) Not every page on the planet needs to allow comments. Frankly, the local CBS news website doesn't need to accept comments on stories. Neither does the BBC's articles. Neither do most.
Of course, they have dismissed everything in this article, so the only thing left is for the government to require every internet user to use their real identity online and then have a single discussion/forum/conversation system that all runs on the same API (or have a standard API that ties together very different discussion/forum/conversation systems). Then, you will have no choice but to post as your real world identity and every comment you ever leave anywhere on the internet will be part of that identity and you will be rated on that identity, always. A truly unpleasant idea and I would rather put up with having to ignore the dregs of the internet versus losing the option of anonymity. Of course, people who live their lives in public often have a different view than this, since their personal desire is to get their own identity out there. Not everyone has that same goal or desire.
(I won't even bring up my distinct hatred of things like Disqus and Facebook whatchamacallit that sites implement instead of drawing up their own conversation tools).