Earlier quoted context omitted.
If it was this simple than Facebook would never have caught on in the first place. The answer isn't "rollback" because clearly there is some value here. The answer is finding out how to maximize that value to our lives, not maximize the payout for investors.
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…
With #2 you'd still need trusted sources that can verify that a person i found via johndoe@acme.com or +1 (914) 555-1212 is in fact the owner of that email or phone number.