I'm very confused by this comment. The era you're talking about is also the era that Facebook was released and it didn't have a voting system, not even likes/reactions. But that's when the term "social networking" really took off, and it definitely referred to Facebook and not Digg or Reddit or Slashdot, to name another that has a comment voting system.

"Social media" as a term comes even later, to capture Twitter and the social features of YouTube and other stuff like that. But it's all sites where most users are people using real names and real faces, and users generally produce content themselves and follow each other's content.

There's clearly a cluster there and HN/Slashdot/Reddit/Digg are clearly outside it. An umbrella that covers both HN and Facebook is almost meaningless; it's "all websites with user-generated OR user-supplemented content."