> Social + Maps = Seeing that my friend goes to this restaurant and likes it.
How would that be relevant to me? I want to know that someone who likes other restaurants I like goes to this restaurant and likes it. I don't care what restaurants my friend likes. We're not friends on the basis of liking the same restaurants.
While I agree with you that it's more interesting to get recommendation based on similar users, most people have a reasonable idea how their friends tastes in various things mesh with their own.
I know that a particular friend of mine is equally picky about his steaks as me, for example, and I'd trust a recommendation of steak houses from him.
Being able to attach a particular name to recommendations helps them attach a level of trust to the recommendation that regular users might be less inclined to attach to "anonymous" recommendations.
If they're smart, they'll also consider similarity in tastes when deciding which of your friends recommendations to emphasise (especially if more than one of your friends have clashing ratings of the same places).
Social recommendations also helps you "break out" of the filter bubble.
E.g. Amazon has a very specific view of what I like to read, and so on. But people who know me will occasionally be able to provide me with other impulses that leads me to try something entirely new that is very different from what Amazon will recommend to me based on what I've read in the past.
What if all they did was mark the restaurants your friends have liked, not changed the search results order? So it's just an attribute. It could have SOME value.
How would that be relevant to me? I want to know that someone who likes other restaurants I like goes to this restaurant and likes it. I don't care what restaurants my friend likes. We're not friends on the basis of liking the same restaurants.