Three reasons for this:
1. Some individuals can't make an argument without comparing their opponents to self-stimulation devices,
2. People that challenged need to be identified so we can help them with their problem,
3. Only English Lit professors should have to type "anon" as much as I do.
The solution (for now) is OpenID posting. How do you get an OpenID? Well, you probably already have one. (Yahoo, Google, AOL, MySpace, Flickr, etc. all provide you with an OpenID). Here's a link to a page that lets you know how to use your long-lost MySpace login and password as your OpenID.