I'm a 40 year veteran of a Telco that is also an ISP and 16 years ago I decided that I needed to learn networking to stay ahead of the curve. Now I do more networking/programming than traditional telco and I can tell you that anyone that programs modern phone systems with IP terminals for a living is a network guy, as well as a voice guy.
I think the problems comes from perception. I think that the business owners feel that the chaps that take care of their computers have a much more complex job than the guys that take care of their phone systems, and I think the reason is that most business people have a decently firm grasp on how a phone works and at the same time, they are (for the most part) clueless how their computers or networks operate, thus (in their minds) elevating the role of network administrator almost to demi-god level, which perpetrates the myth. In my experience, most network guys are great at Microsoft and Linux and C++, but are clueless when it comes to the transport side of the network (switches, routers, LAN-WAN, etc).
"If I had known it would turn out like this, I would have become a locksmith" Albert Einstein
NCSS, NCTS, NCTE, CS1000E, Avaya IP Office, Mitel 3300 Basic & Advanced, 5000, SX200, NuPoint