I don't know if this is any kind of a groundbreaking thought, but it occurs to me that these social media platforms began as entertainment. Only more recently have they become sources of information and opinion.
Moderation of entertainment is almost completely acceptable within the bounds of a given platform. First, it's privately owned so the 1A is not implicated, and owners/curators are free to curate the content of their platform in accordance with their "goals," to be family friendly, to be hardcore porn, to be funny, or musical, or whatever.
It is only once these platforms, somewhat inexplicably, became fora for information and public debate that content moderation is even questionable, even if on "sub-legal" grounds.
It's the opposite of news. What was once serious news has become entertainment, and what was once frivolous entertainment has become news.
The problem is, entertainment is attractive to the morons, while actual news typically is not. Similarly, those seeking to be informed avoid entertainment outlets when that is their goal, or maybe even altogether, to a large extent.
We're having this fucked up convergence between news/information and entertainment. It has been recognized on the news end of things, somewhat less so on the entertainment end.