If you try your hand at machine learning, you learn very quickly that 95% of your amazing bright ideas don't work. The thing you learn by reading about popular algorithms isn't how ingenious they are - their popularity tells you the key fact that they often actually work.

Google is an AI company, they just don't advertise the fact. It's quite possible that someone in Google already tried an approach like this, and found that it didn't really work. A lot of people had similar ideas about the Netflix Prize and it didn't work for them.

I don't mean to sound too discouraging here. It's just that brilliant new notions for data you can integrate into your AI algorithm (and search is an AI algorithm) more often than not turn out to simply... not... work. So you don't get enthusiastic about an idea like that because it sounds good - you really do have to try it. If it turns out to work great in practice, like PageRank, then you might have a Google killer on your hands. It's just that the practical performance is hard to guess by eyeballing what a good idea it sounds like.