The main thing Facebook provides that isn't addressable with the systems we'd be left with in a "rollback" is a universal way to stay linked to other people that provides both people with control over whether that link exists or not. Everything else is just features glommed on top of that basic feature.

AFAICT there are only two ways to provide that basic feature:

(!) A centralized service like Facebook that manages the identity network. Any centralized organization is most likely ultimately going to exploit the fact that they own the network for their own gain, financial or otherwise.

or

(2) A decentralized service based on the similar cryptographic math as bitcoin, where every user gets one token representing their identity, and some sort of way to propagate changes to their identity signed by that token to everyone they are connected to and this needs to be accomplished in such a way that you can always re-establish the links to your friends in the network to be able to sync data.

I can't even begin to imagine how you'd develop the latter into a form that would be usable and therefore adoptable by the average person.