I am unsure if anyone is still having conversations about whether or not Facebook alone will beat Google for overall Web dominance. Frankly, I don’t think they will and I know others agree with me.
That being said, a few things which do make Social so appealing however is the fundamental difference in behavior from users :
1. Users are much more likely to be “real” when dealing in social since it is their reputations are on the line.
2. Social is a more, dare I say, passive method of discovering content. There are no actions taken or searches performed and yet, it works.
3. Open Graph, which I continue to stand on a soap box about. Optimizing your Open Graph tags is a huge opportunity for marketers.
All that being said, from a search engine standpoint we know social is important. Google has made it clear that they pay attention to Open Graph signals.