Why?

A couple of good reasons (there are more, but this should suffice):

1. Blog comments do not attach any accountability to the commenter. There is zero penalty levied for abusing the system, either as means of narcissistic catharsis of sleazy commercial opportunism. Nature hates a vacuum, and there's a "consequence vaccum" surrounding blog comments. With no barriers to entry, and no penalties for abuse, it shouldn't surprise anyone when we note that blog comments are increasingly filled with noise and abuse. It's surprising that it worked as well as it did originally.

2. Blog comments are blog posts! Or at least they should be. There's no reason to have a "Comments" section for every post -- that's what the TrackBacks section is for. Want to respond to this post? Great! Post your responses on your blog, and send me the TrackBack. Should I want to respond to your lucid insights into my original posts, I'll just post a reply right back, and send you the TrackBack for that. And so on...

You don't have a blog of your own to respond with? Not a problem. You can spin up your own blog in just a couple minutes, for free, at any of a good number of services. Respond all you want. At length. On any topic. You don't even need to publish original posts. I can imagine an interesting "comment blog" that consists of nothing but witty and insightful comments in response to other current blog posts. Come to think of it, that's all some of my favorite blogs are...

A Self-Correcting System
Requiring commenters to publish their comment on their own blogs gives the system a wall to self-correct. If a commenter wants to be abusive in response to something I've said on my blog, be my guest. Just do it on your own page. Go ahead and notify me, and I can do what I want with it: respond in kind, quote the acceptable parts in a subsequent post, or just ignore it. Want to publish a link to a miracle cure for male pattern baldness in response to this post? Be my guest. Just do it on your own page. Feel free to ping me with a TrackBack to let me know your link is there, and I'll do the right thing in response. I promise.

The tables turn right around when commenters have to use their own space, even if its free, to give voice to their comments. Bad behavior and abuse is naturally discouraged, it just makes the originator look bad, if they get noticed at all.

What About The Good Guys?
For good commenters, other, virtuous things happen. If all my comments were hosted on my blog, I again "own" and control the content I originate. I can get credit or blame for it directly. Those interested in topics or keywords discussed in my comments can navigate to my blog.

As trust relationships develop between commenters, the conversation can still happen in both places automatically. If I respond to a post from, say Doc Searls, and he decides after cautiously trying to wade through my blog that I'm harmless (if not particularly lucid) as a commenter, he can automate the posting of my comments that arrive via a TrackBack. That is, when I send Doc a TrackBack in response to his post, he could configure his blog to automatically grab my comments from the TrackBack and append those to the original post in his blog. Overtime, Doc's "web of trust" would evolve to include a great number of responsible commenters, and the conversation would evolve as automatically as it does now. New commenters can still be allowed; Doc Searls would just have to go through the TrackBacks for commenters that aren't automatically published, and grant access to the ones he thinks merit publishing.

What would be needed to make this work? Just a couple of things, one easy, one a little more tricky.

First, a simple link to be placed at the end of blog posts that invited comments, but offered either a) the TrackBack URL for commenters who already have a blog to send their responses to or b) a redirect to a blog host of choice that provides a quick and easy setup process to spin up a blog, if even just to comment on the one provocative blog post. If it were b), response information could be preserved through the setup process so that the newly initialized blog appears with a new "response post" -- linked and quoted to the original post -- as the first order of business for the new blogger.

The second piece of the solution would be a policy system for TrackBacks. This could be arbitrarily complex, depending on the tools and the blogger's appetite for configuration, but minimally there would need to be a way to manage TrackBacks in a way similar to the way comments are moderated by blog tools today. The administrative interface for the blog tool would display the contents of the TrackBack -- the content on the commenter's blog -- and the blogger could make "Yes/No" decisions about whether to publish the TrackBack as a link, as pulled, quoted content, or not at all. Bloggers who qualify for the "White List" could have their TrackBacks linked or quoted automatically, without any added work for the blogger.

Blog Explosion
Last but not least, think of the "hype curve" benefits of such a setup. Blog numbers would explode. David Sifry's "State of the Blogosphere" charts could go super-geometric, with blog numbers doubling not in a matter of months, but just a number of days, or even hours, as the commenting masses migrate to "comment blogs".

Ok, so that last one's not really a good reason to pursue this. But the other reasons are good ones, I think.

Comments?