> are heavily - and sensibly - regulated utilities. They are understood to be companies that operate in a very different business environment from the majority of other businesses.
Yes, this is what's under discussion. One side of the debate thinks that the big social media products are critical enough to societal (and especially political) discourse that access should be guaranteed through regulation. It's a rather radical claim, and not one I'm sure I agree with, but it's not self-inconsistent.
> And remember that a power company can cut off power to people if they are intentionally attempting to disrupt the power system, or simply not paying.
Yes, and FB/Twitter can ban people for plenty of reasons that no one considers particularly controversial or critical. As with the power companies, the claim is that doing so for expressing legal-but-unpopular political speech is not conducive to the health of civic discourse and thus democracy.
> Power companies (1) get paid by their users
I don't see what this has to do with anything.