Earlier quoted context omitted.
> We can't really compare them to the government until they have a standing army. While I disagree that the firms in question have government-like comprehensive power, even without their own army, a monopoly or coordinating oligopoly able to lock out new participants on essential communication services would have such power, and be a de facto part of the government, even if they lacked formal command relationship ove…
There is a lawsuit where a company owned this mining company town, including all of its roads and sidewalks. A Jehovah's witness won a lawsuit on the basis of the First Amendment, enabling her to walk about that town and distribute her pamphlets. https://www.youtube.com/watch?v=lBozijndSLc Originally, it was widely recognized by US jurisprudence, though property rights and freedom of association are important, the Fi…
And when a single company has similar control over the internet, even for a particular group of people such that they are otherwise unreachable (as AT&T once did nationalky over telephone communications), Marsh v. Alabama might be relevant (It might not, since active relaying is not the same of not denying access to property, and is itself an issue of the first amendment rights of the party who would be compelled to relay the speech.) That's not the case now, and the Marsh v. Alabama doctrine does not compel internet companies to relay content they don't want to, see Cyber Promotions v. America Online.
> Originally, it was widely recognized by US jurisprudence, though property rights and freedom of association are important, the First Amendment was even more important.
The issue with regard to relaying is neither a free association nor a property issue, but a free speech/press issue—whether the state can compel a party to actively participate in relaying ideas that they do not wish to participate in.