Sorry, in what way are the dominant social media websites (Twitter, Facebook, and Reddit in particular), NOT main stream media in 2020? Certainly they aren't p

Sorry, in what way are the dominant social media websites (Twitter, Facebook, and Reddit in particular), NOT main stream media in 2020? Certainly they aren't part of the legacy media, but they all seem to carry water for the same narratives and ideologies. The non-mainstream media is publications that people in polite urban mostly-coastal American culture sneer at: Breitbart, The Post Millenial, Reason, Parler, Gab, specific independent journalists on some of the mainstream platforms, etc. But certainly Twitter, Facebook, and Reddit are media and they are mainstream. And they have demonstrated their willingness to censor stories with more or less the same bias (in the same ideological direction) as the mainstream legacy media. They're just the mainstream new media.