The more effectively something does its job, the less superficially useful it appears to be.

If I have effective locks on the doors and windows of my house, as a result of which no-one breaks in, it will seem as if the locks are unnecessary. If I keep my car well maintained, so that it never breaks down, it will seem as if all that expense on maintenance was unnecessary. You don't see the casual thief who tried the door and went away, or the timing chain that never snapped and wrecked the engine. When there is no crime, it seems that the police are unnecessary; when no-one tries to invade, that the army is unnecessary. In places with clueless management, the more effectively the computer support staff do their job, the less reason management will see to employ them.