I've thought about why usenet died and blogging seems successful:
- tight control of authorship
- inherent facilities to control comments and spurious posts
- distributed architecture with no authorship control
which of course makes usenet news incredibly robust and difficult to (a) censor (b) stop sprious posts. Blogging, while seemingly as anarchic as usenet does have tight individual control and of course there are a lot more blogs than usenet groups - so people who are researching the wearing of socks in the later western roman empire create a blog rather than posting to a group, so the people who read the blog are only other researchers interested in the area and possibly the odd sock fetishist - ie the potential audience is smaller.
The only question is why do the loonies continue to post to usenet news - havn't they noticed that usage as dropped way off for the text groups?