It isn’t that Facebook or Twitter aren’t communities but that social media companies self-promotionally call them communities while actually treating them merely as userbases. Social media platforms are, and contain, communities—sometimes singular and solitary, sometimes cross-pollinating and overlapping, sometimes fleeting and ephemeral. How what’s treated by the company at issue as just a userbase itself makes use of the platform often is more about the users than the makers. I’d have less of a problem with the companies themselves referring to their users as a community, or communities, if they ever considered them that in any way other than rhetorically.