Recommendations?

While reading Nina Simon's book this week, I was a little confused by the whole recommendation systems she mentioned. I thought it was cool how she compared these recommendations to ideas like Netflix to make them easily understood, but I was a little confused as to how they actually fit in with museums. I understand that museums are always looking for ways they can improve their visitor satisfaction but I'm unsure as to how using recommendations from visitors are going to achieve that. I mean they can certainly use these suggestions, but there is no way they would be able to do all of the suggestions given by visitors!