The majority of US citizens agree with the very narrow limits on free speech defined by the Supreme Court. Only a fringe minority want much stricter limits, or no limits at all. Twitter could potentially align their content policy to match US law and stop censoring legal content, although that would make it less valuable to some advertisers.
> The majority of US citizens agree with the very narrow limits on free speech defined by the Supreme Court
Do you mean to say that the majority of people believe this is how private companies should operate? If so, Id love to hear your reasoning for thinking that, because I would disagree heavily.
Saying racist stuff is legal, but its still going to get you kicked out of almost every bar, with few to no complaints from other patrons.
Not really, most of 4chan is moderated (albeit inconsistently and often capriciously.) I think the defining characteristics of 4chan are anonymity (from other users anyway, with some caveats) and the culture/reputation of the website.