When you want to do voting, moderation, new/hot/etc, handle potentially large loads, it can get to be a lot. Also, if you don't want anonymous commenters (becau

When you want to do voting, moderation, new/hot/etc, handle potentially large loads, it can get to be a lot. Also, if you don't want anonymous commenters (because that contributes to spam and bad community) you get into the entire user/password management mess. Particularly if you're just some guy that wanted to blog stuff, rather than a content-centric media corporation. Plus there's some potential benefit to having a consistent identity across different sites. FWIW, Facebook was doing the exact same thing. I think they still do, though I don't see it as much.