Isolation from friends and family. Like not being able to go to your moms house because her neighbor might try to kill you and her if he discovers she is your mom.

The conclusion "no facebook = severe social isolation" (including being cut off from ones own family) only works under the assumption that basically everyone everywhere forgot how to socialize without "social" and that interaction without facebook is somehow impossible or at least hard. This assumption is maniacally and laughably absurd. I can not even fathom how the planet might look where such a statement might sound reasonable.

Although you're right that it's no impossible, it is much harder. It's like default values on software products. The easier something is, the more people will do it. Lots of things are harder without Facebook access, like accessing photos from a family member.