If you asked someone "What is it that anchors a brand, product, or service-oriented online community, or other social application?" what would they say? If they answered, "the brand, product, or service..." you'd be right to question it further.
It's not a trick. It's a realization that brands, products, and services - and the things related to them that you want your customers to know about may not be the same things that they are interested in socializing around. Product spots on TV aren't "social;" they're an interruption to the things that are themselves social. That they feature a product and make the case for why someone might consider it further is the entire point of the interruption.