Thanks for the insights. "Going to an airport for identity verification" sounds a bit extreme, but I guess if that's what it takes, then so be it. Will they actually close such accounts or cancel the award ticket, though? (For people who've never credited to FB but are not committing fraud either)
I have no personal experience and anyway it would just be a sample of size 1.
But as systematic reader of this forum, I do not think that we got any bona fide member who could not finally get their FB ticket under such circumstances (new FB account, no flight activity)
And we have not had recent posts about such occurrences.
In the murky situation where the miles were transferred from a cc with different name than the pax travelling, then the answer is less clear. Some posters might have been bartering award tickets and stopped posting.
I don't remember any case where a guy opened a FB account in his name, transferred miles from a cc, then issued an award in his name and could not get his ticket validated in the end.