A blog without comments is wrong. I feel a twinge of discomfort when I come across such a blog. I think I'm beginning to understand why.
Blogging is an act of egocentricity: come read me because I have something interesting to say. Come back again because I'm regularly interesting.
Adding comments to a blog softens that. It's a willingness to listen, an invitation to conversation. Blogs without comments, on the other hand, twist the dagger: I'm interesting, I've said all there is to be said, and you couldn't possibly say anything worth hearing.
For instance, I'm probably going to drop the Reverse Cowgirl from my reading list. She's been a fun, guilty pleasure for some time. In recent months, she has leveraged her blog presence into one of minor celebrity. While visiting today, I noticed the comments had disappeared. I felt an axis-tilting change in the relationship. I didn't feel like a welcome guest anymore.
As another example, Halley publishes a blog I've never enjoyed. Best I can tell, Halley's claim to fame is she blogs a lot. A lot of people read that blog because ... ummm ... I don't know. I've just found it irritating. To test my theory I went and visited her blog, and sure enough: no comments.
David has a thing for skewering A-List bloggers. I understand and share some of his irritation, but not all of it. There are some A-List bloggers I enjoy reading, such as David Weinberger and Larry Lessig. These guys have comments on their blog. Maybe there is some correlation. The fact that they are willing to listen makes me feel welcome. Totally not irritating.
So far, I've only found one comment-less blog that I want to keep on my reading list. That is Ed Felten's blog. Although he doesn't accept comments, he does take trackbacks. That mitigates things a bit; it at least gives somebody a chance to respond. Still, I get a small whiff of that, "I don't care what you have to say" thing whenever I visit.
What I'm realizing is that--good, bad, or otherwise--I'm insulted by blogs without comments. It's the same feeling as going to a party, having somebody yack at you for five minutes, and then they turn tail and run before you can say anything. I think it's rude, and I don't enjoy hanging around those sorts of people.