Why? Because 75% of new accounts being created there lately have been created by spammers using automated tools. Spammers took over Ma.gnolia. Now, the company is using OpenID as a system of 3rd party verified identity and using the superior spam blocking skills of services like Yahoo! and AIM to clean up the Ma.gnolia ranks. Spamfighting could be the incentive that puts many other vendors over the edge to leverage OpenID.
At best this is a Club solution, meaning it’ll be effective as long as Magnolia is not a worthwhile enough target or not enough people use the technique.
Anyone advocating that a Yahoo, Google, or AOL account is going to stop spam signups, sploggers, or anything of the sort is out of touch with the dark side of the internet. The going rate for a valid Google account is about a penny each. For $100 get a text file with 10,000 valid logins and passwords, and go to town. We used to require email verification to signup for WordPress.com, and the vast majority of splogs were coming from Gmail or Yahoo email addresses, hundreds of thousands of them. Myspace and ICQ are both good examples of completely closed identity systems with registration barriers but still overrun with spam.
Each of the big guys probably has an anti-abuse team larger than all of Magnolia fighting these spam signups, but it obviously hasn’t been effective. In theory you could blacklist OpenID providers but who’s going to block Google and Yahoo and even if they did they’re just pushing the problem outward, to the point where spammers eventually run their own identity providers, and if you think they won’t come from millions of unique registered domains look at your comment spam queue.
OpenID has a ton of promise for the web — let’s not hurt it by setting people up for disappointment by telling them it’s a spam blocker when it’s not. Regardless of registration, identity verification, or CAPTCHA, you still need something working at the content level to block spam.