I see this all the time. I love to have a communication with the blog author, or at least get the sense of it. But if I comment on a blog and I don't get any response, I won't be coming back. (Even worse is if I see that the author has made new posts.) For me, the blog could as well been operated by robots. Why enable comments if you'll never comment yourself?
I'm not talking about blogs that get over 50 or 100 or 1000 comments on each post. Just normal gaming blogs with usually zero comments per post.
And there's no excuse, really. You can get e-mail notifications on (I guess) all blogs today (in the control panel, I mean, so that you'll get an e-mail every time someone makes a comment).
I've been thinking about this phenomenon for a long time now. I mean, if you have a gaming blog (or one for your fabulous new free game), you know how hard it is to get visitors. Why drive them away by not paying them any attention? It only takes one second to write "Thanks!".