There's also a social component to blogging, right? When you post something it tells me about who you are. It helps establish my (probably parasocial) relationship with you.

And when you post something, I might be interested in it, even if I wasn't interested when someone else posted about it, because I'm interested in you and interested in what you have to say.

I think that human communication is about pure relationship socialization as much or more than it is about actually communicating information or ideas.