Social marketing means making friends not selling stuff.
It works because it is true.
Would you consider buying something your friend likes? You would.
Would you follow a food truck or a VC deal stream if you were looking for gourmet tacos or potential startup clients? You would.
Pro photographers post images on Flickr, make friends with photo editors, and they get work.
Fashion brands create Facebook pages and make tens of thousands of friends, and get the new loyalty discounts.
Dale Carengie's book was never more apropos: How to Win Friends & Influence People.
Here's an exercise in Social Media: "Friend me" on LinkedIn or check out the "classic" social networking presentation, What The F**K Is Social Media then tell the author I said, "Hello."