I agree that there are most certainly alternate means by which a social network could be funded. Subscriptions, pay-per-use, and public funding all come to mind. I don't agree that this invalidates my previous points about phone networks and their history. New technologies enabled prices coming down because a long history made it worth investing in. Nothing about those technologies or price reductions was inevitable.
I can think of several plausible ways to split up Facebook. The one I can think of that adheres most closely to the basic utility model would be for only the most foundational service to be handled by a regulated monopoly. That, I expect, would be a pseudonymous social graph where people can add and remove connections. Anything on top of that would be handled by third-party providers.
I can imagine other services that some people might consider foundational and thus desire to lump in with the above. Some might consider posts, walls, profiles, and groups part of it. Some might even consider chat part of the foundation.
The "online rope-a-dope" you describe is my attempt to avoid telling people that I am reasonably sure they are being silly. It's always possible that there's genuinely something I don't understand about the positions. It's happened before, it's happening now, and it will continue to happen in the future. It generally doesn't, but telling people I think they are being silly is generally not conducive to productive conversation.
Being over-the-top syrupy nice tends to go over better than pointed criticism, which tends to make people defensive. For example...
Under which set of laws would Facebook be nationalized in your proposal? American? French? English? Turkish? Saudi? What effect would this have on effects to combat fake news and hate speech? Whose definitions of "fake news" and "hate speech"? How are you going to make sure that users don't migrate to a new, better, and non-regulated-monopoly social network the way people migrated to Facebook from MySpace? Are you just going to take over that one too? How do you propose to ensure that client app developers with access to the ruling council don't use their position to push away other client app developers?
These aren't pointlessly detailed questions. They're ones that spring to mind almost immediately, and ones that any serious proposal that merited consideration would need to wrestle with. Some of them are major points of public policy which differ very significantly from polity to polity.
I would like to understand that you've gone through these questions and arrived at good answers. I want that to be true.
You're probably feeling defensive right now. A little attacked. Which is why I couched the whole thing in asking you to help me understand, because a person who feels attacked is not a person who is genuinely listening.