This isn't a specific criticism of this site, as such, but rather on all such sites that try to save people time by providing generic logins.
Not that you shouldn't do it. It's just worth thinking about, y'know?
Sure, there's a good argument for anonimity, but it's give-and-take in the virtual world. You're basically getting something for nothing and robbing the site owner of their ability to proscribe the means by which new users are given access to the site.
Also, that any data I provide about myself is stored in some other persons/companies database, with some unknown level of security, you will never get real information about me unless I have a real sense of trust of the website, and there is an obvious need for the information related to use of the website.
So by messing with the accounts, you deprive them of that data. That said, I would assume they're smart enough to see that an account that gets logins from 100s of IPs a day is obviously not one person.