When the term first came about, it was mainly used to contrast with what was around earlier.
"Earlier" could be anything from Usenet to forums etc that were based around topics. Your view of content was based around the topics you selected. You followed topics.
A social network was where you connected with other people, and your view of content was based around who those people were and their activity. You followed people not topics.
That's definition I'm sticking to, and why I don't regard reddit or HN as a social network. Although on HN doesn't really have topic following functionality, you just select topics on the fly.
"Earlier" could be anything from Usenet to forums etc that were based around topics. Your view of content was based around the topics you selected. You followed topics.
A social network was where you connected with other people, and your view of content was based around who those people were and their activity. You followed people not topics.
That's definition I'm sticking to, and why I don't regard reddit or HN as a social network. Although on HN doesn't really have topic following functionality, you just select topics on the fly.