The error is assuming that everybody else agrees with your definition.
Some of that is for a good reason (privacy), much is not. Why can't I copy backup remix my various social network data? Right, corporate control
Though a de facto oligopoly in the social media space means that your reach could be greatly reduced (though not, as you note, eliminated) if you are deplatformed. I imagine that some politicians, entertainers, and businesses could see large effects.
Being delisted from Google search could also be an issue for businesses due to Google's search dominance.
If twitter and the government work together (e.g. twitter banning people that disagree with the government to get favors or avoid punishments) then that should be treated in a similar lense as government action.
It becomes interesting if it turns out that there indeed exists a symbiosis between the US government and social media companies wherein the latter are compelled to do censorship laundering on behalf of the former, maybe in exchange of their balls being not so tight in the regulatory vise. After all, it’s not censorship if a private company does it, right? Right? (wink, wink)