" Simply put, the networking group should maintain and configure network devices, and the security group should maintain and configure security devices."
Ah, I also sometimes lament that this world should be a simpler place :-) So, pray tell me, what is a firewall: a network or a security device?
Got this one? How about a switch firewall blade in a switch?
Oh, got the above OK? Here is a tougher one: a firewall code in a router?
Got my point!?