Facebook already possesses and uses this sort of personal information for ads and they still don't have a great monetization rate per user. Twitter certainly has less overhead per user though.
Exactly. This is the same tired argument that we've been hearing about the FB's and MySpaces forever. Logically, it makes perfect sense. In reality, nobody has figured out how to actually monetize this sort of activity yet.
Actually, it seems like the argument is subtly different. Instead of trying to guess what we're looking for, this would try to answer what we've explicitly asked about. It's like the difference between your friends randomly telling you what car you should buy and them answering in response to your question about what car you should buy.