AOL used to charge by the hour, and discovered an unintended side effect when they switched to flat-rate pricing. Mods in the ancien regime had been compensated by getting free online time, but under the new system, that became worthless, and there was a wave of mods quitting because somewhere-around-minimum-wage had been sufficient compensation for the double binds before, but they weren't about to volunteer to deal with the worst of forums.
https://www.wired.com/1999/10/volunteers/
"Everything changed in December of 1996, when AOL moved to a flat-rate pricing system: unlimited access for $19.95 a month. Gone were the profits from hours spent in chat. Worse, chatty members clogged AOL's servers and threatened to crash the system. Gone too were many of the volunteers. Without the hundreds of dollars worth of free hours, more than half left."
Nope. This battle has been fought in newspapers and television, so I expect at some point that it will be settled by legislation or the FEC. If they block more of one party over the other, expect the lawsuits (frivolous or well thought) to start hitting. Trying to be the moderator to people who can change the rules of this game is not a good position.
The similar battle in newspaper and television included heavy moderation and legislation to limit this. E.g., do you think the Wall Street Journal was regularly publishing letters to the editor that focused on the arguments for abolishing private property?
The only legal question unique to social media is the 230 provision that protects a platform from legal action from third parties due to hosting user-generated content. That is still an open question. Social media companies always have the option to apply stringent moderation and declare themselves a publisher. They could even do this selectively. E.g., a newspaper with an online presence still receives 230 protection for user generated comments on an article when there is a clear denotation differentiating what is published by the site and what is user generated.
Advertising is different than letters to the editor. There is a rather large bit of law on the what and how of campaign advertising. It actually dates back quite a few years.
The moderation as in "I don't want to see XYZ because offended" is easily solved. The moderation as in "I don't want the other guy to see XYZ because he's too stupid to realize the wrongs" is obviously not solvable because the other guy has his own ideas - double bind as dang pointed out.
I'm bemused. In the last few weeks, multiple stories have cropped up about various advertizers boycotting FB. On every one I saw, the cynics were buzzing about how the companies were only making profit-based decisions and virtue-signalling by characterizing their cessation as a boycott.
But it sounds like they hit FB in the wallet and that got FB to take notice.