The term "social media" became popular with profile-oriented sites like MySpace and Facebook, and for a lot of people like myself, refer to that type of site.

The term "social media" became popular with profile-oriented sites like MySpace and Facebook, and for a lot of people like myself, refer to that type of site. They're about being social, not about topics, like forums are (which predate profile-oriented sites). By that standard, HN isn't social media.