But others have come to the same conclusion. So I'm pretty confident that having comments does benefit the blog post itself ranking-wise.
The fact that a post is more likely to be found means that it will probably generate still more comments. So the process continues ...
Apart from this SEO benefit, there's also the "social proof" aspect of comments. When people find your post and see that some readers have commented, it makes your blog immediately more appealing to them. It's "alive", so to speak.
Also, if you have one or two comments already, you're likely to get more. This phenomenon reminds me of what occurs in dance floors in nightclubs. The music starts and no one is game to get up and start dancing. But eventually one person (usually a woman!) plucks up the courage to do so. One or two others tentatively follow, then they all jump in at once.
So getting that first comment is crucial. That's why it's a good idea to invite comments, or finish your blog post with a question when appropriate. Another way to "get the ball rolling" is to write some really good comments on other blogs. The owners will often show their appreciation by writing comments on yours.