I wouldn't consider it social media since its lacking a lot of the aspects of "social" like tagging or checking into places, posting family pics, the "social" fake comments... its a private board where we come to gather because we share a common, I would even say unique passion.
I take breaks from social media from time to time... its a way to keep in touch with people that aren't necessarily close by. But like Reborn said, they collect, trend and profile our digital lives for sales/marketing and soon this Meta world Facebook is building.