Yea, maybe a few businesses would fail, maybe some people would lose contact with old friends. But if fb is the only way you keep in contact with someone, do you really care about them?
Cost benefit analysis is easy to do, actually pulling the trigger is hard.
I'm certain LinkedIn was doing it as well, ie. dark patterns to upload contact list then aggressively harvesting new users.
I'll push the damn button, no problem. Just show me where it is. However, I'm guessing it's harder to find and is actually split into 7 horrocruxes.
Now, all the people in a position to do so are chained by perverse incentives to keep the whole shit show going.