You have have a right of speech (with very limited curtailments) in the USA... However given high density of people on limited technologies, if you're on the out, you have no effective right to speech.
And since political candidates are on there, you even lose the forum to talk with them. (AOC, Trump, other national politicians, local city councils, county councils). When the soapbox IS twitter, Facebook, Reddit, Instagram, Snapchat - just how much power should the corps yield to decide who talks and who doesn't?
(I'm making an argument for a review on user density relating to a monopoly and thus significant oversight and access, esp when relating to politicians and their constituents.)