But these social media platforms are clearly communities... they even have "community guidelines". Not to mention Github https://docs.github.com/en/site-policy/github-terms/github-c...
at best, fecebutt and the like are fora where communities can form, as long as management tolerates them
Any one community within is free to set its own rules and conventions (for instance, I'm on a community noticeboard group where business posts are only allowed a Monday), but those communities have absolutely no influence over the policies of the platform as a whole.
Well, if they have community guidelines… this definitely makes them a community, lol.