I mean, it's a matter of pedantics and subjectivity.
Technically, Social Media is a super set of all of those things. They're all media platforms that primarily operate around user socialization (aka engagement). They are, by definition, social media, and in turn social media has been around long before Facebook (eg, slashdot, BBS, Usenet, etc).
I do agree there's a difference/nuance to be recognized here though (eg, old web vs new web social interactions). I think user vs content focus kinda misses the mark, as the truly key differentiator for me is what influences the activity, both in terms of driving people to post in the first place, but also in curating what they can('t) or should(n't) post. In other words, is the platform a community trying to serve it's users, or a company trying to serve it's stake/shareholders?
Technically, Social Media is a super set of all of those things. They're all media platforms that primarily operate around user socialization (aka engagement). They are, by definition, social media, and in turn social media has been around long before Facebook (eg, slashdot, BBS, Usenet, etc).
I do agree there's a difference/nuance to be recognized here though (eg, old web vs new web social interactions). I think user vs content focus kinda misses the mark, as the truly key differentiator for me is what influences the activity, both in terms of driving people to post in the first place, but also in curating what they can('t) or should(n't) post. In other words, is the platform a community trying to serve it's users, or a company trying to serve it's stake/shareholders?