Eh, not so much. The invisible hand is constrained by government regulation, including Section 230 protections.
I would also propose another analogy: Big Tech monopolization of social media is analogous to a wealthy land owner buying up all of the land used as the "public square" or "public forum" buildings in every town, and then asserting private property rights to control the dialogue/discourse in the erstwhile public forums. Social media have made themselves the de facto public forum of the internet age (which they have done, in part, by consolidating a monopoly of social media and by driving all internet discourse away from independent blogs/sites/forums and toward their own platforms), and thus they have a direct impact on the ability of the individual to exercise freedom of speech.
Nah. It's a myth. I'll not argue the point here in the election thread.
As this pertains to the election, I agree with the analogy you propose. It's still not a constitutionally relevant point though, but is most definitely a denial of free speech.