For instance, you can invent a new category in order to avoid detaining people like criminals or war enemies if none of the laws applying to those are convenient.
It does make me wonder what they'd use for justification - prior to the current administration. The current administration would just use nationalism and protectionism, I'd think. I'm not sure how the previous administration would have framed it in order to make it politically feasible.
There were services that came before, but they lacked the inertia the current incumbents have. The userbase of Facebook, Google, etc. is huge in the Western world. Even if another company came along and built a great service, I doubt it would see mass adoption due to the massive numbers involved with the current providers.
Banning Facebook would actually give a boost to their productivity, not much to lose there.