I just noticed on my FreeBSD machine that root is in wheel and operator. I'm trying to think of a situation where UID 0 being in a group would have any effect on... well... anything, and I'm coming up blank. For that matter, does root even need a primary login group in /etc/passwd? Or does login(3) choke and die if the user has a blank primary group field?
(To clarify: I understand the purpose of the "root" group's existence, since files need a group owner. I'm not understanding how it matters that the user root/toor/whatever has that group membership.)
Is this just cruft from decades ago, or is there a real reason for it?