Only if you think forums, 4chan or whatnot from ye olden days are also "social media". HN has no friends feature, no curated algorithm, no way to discover creators...
I do. Primeval social media, sure. Social media that predates the term "social media," even. Nearly all things exist before we agree on a name for them, so that's nothing new.
All of those services you list are examples of an online medium that exists for the purpose of socializing. So yes, they're all forms of social media, even if they're considerably less structurally harmful than something like Facebook.