It's the same principle that spy agencies rely on. A spy agency cannot survive one compromised spy rolling up the entire spy network.
One could reasonably posit that Germany lost WW2 because they used Enigma for important stuff, and when Enigma was compromised, their operations were compromised thru the end of the war. For example, Enigma was the cause of Rommel's defeat in Afrika.
The MBA-ification of the world seems to have created an archetypical believer among its other many evils.