I first heard about OpSec from Roland Dobbins with Arbor. Really smart fellow who has many suggestions on network design / defence.

I just think people need to specialize in their field (+ a general knowledge of how the overall systems works).

Almost how a carpenter, plumber, and electrician each specialize but probably have a general idea how everything works. Do you really want a plumber building the foundation of your house? Just seems a little silly to me. Each domain is so large that I would rather have deep expert knowledge in a area than a general handyman who might cut corners or waste time with solutions he doesn't know about.