I define "social media" as anything that manipulates content visibility based on metrics that aren't related to the content itself or user's direct inputs. Because of deliberately deceptive terminology in play this definition will inevitably sound kooky.

Yes, BBSes/forums, chats, NTP news groups and mailing lists are not "social media" in my book. It's important to note that the word "social" in social media was always a kind of marketing ploy.