It has to do with security clearances. It would violate the terms of your security clearance agreement to create ANY type of Facebook account, whether under your real name or under any type of alias.
There is another point to consider. Some people CANNOT join Facebook because
of their job requirements.
I'm genuinely curious. I realize that some people may have job requirements
that would preclude them from signing up for FB with their own, modern name/
information. But, how would a job keep one from creating a "FB persona"?
I have a friend who works for an excessively conservative company, who
did just that, so that the people at her work wouldn't know anything about her