Jim -- The court's point is that you need to find, and sue, the originator of the content that you think is defamatory, rather than an intermediary. There are ways to file "John Doe" complaints to get to the identity of the originator, and courts who have a real, good-faith defamation claim in front of them will help the plaintiff get that information. My own view is that defamation law, like the "derivative works" right in copyright law, was designed for another era and doesn't fit the one we're in very well. But that's a discussion for another day.