Blogging = attention deficit?

One of the things that I find remarkable about blogging in general and our little experiment in particular, is how easy it is for everyone to talk about their own stuff, rather than to really interact with others. I don’t think this is an automatic result from being online, because in discussion forums and on old school systems like Usenet, you see real discussions rather than the more or less random thoughts that pop up a lot on blogs. Would it be fair to say that successful bloggers manage to stick to a subject, even if it’s set by someone else, while people who dabble in it don’t seem to be looking much further than their own thoughts and keyboard, and are usually not very successful at blogging?