People are ordinary
Most people are ordinary, which means that most people are going to produce lame and boring results. Not through any fault of their own, but because they will be ordinary results, and we're simply just not very interested in the ordinary because there's so much of it. By and large we're driven to the exceptional, the rare; to what stands out.
Thus, the inevitable but often overlooked result of people being social on the Internet is a lot of ordinary, boring blogs, home pages, band sites, and so on. This is not because people don't have anything to say; people have a lot to say, as the growth of blogging shows. It's just that most of what they have to say is ordinary.
This holds true no matter how good people's output is. If everyone writes well, or designs good home pages, that becomes ordinary and we start looking for the even better. The quality bar is always set to 'better than the run of the mill', no matter how good the run of the mill is.
Of course a certain amount of people's output will be worse than ordinary, and some of it will be very bad indeed. And as the overall population grows, there will be more and more of the low end, because a rising tide floats all boats. (Then one of the minor effects of the Internet kicks in; as the absolute amount of something increases, it becomes easier and easier to accidentally stumble over it.)
Hence, it should not be surprising that much of what you find out there on blogs, LiveJournal, and other places where people share things on the Internet is ordinary (and occasionally horrifying). If anything, it's actually a good sign; it means that a lot of people are using the Internet to be themselves.
(As with PeopleAreSocial, I doubt any of this is original to me.)