Collaborative filtering is the obvious way to make a scalable restaurant ratings service. Google tried to do it and apparently failed; then Yelp tried to do it

Collaborative filtering is the obvious way to make a scalable restaurant ratings service. Google tried to do it and apparently failed; then Yelp tried to do it [http://officialblog.yelp.com/2013/06/whats-nearby.html http://officialblog.yelp.com/2013/06/whats-nearby.html]. Not being a Yelp user myself, I don't know if they are still doing this. Anybody have insight into whether Yelp is still personalizing recommendations or why personalization hasn't worked in restaurants (in contrast to e.g., Netflix)?