If you were to ask Bob: "Hey Bob, how do you know you don't need to know anything about technology X? What makes you think it wouldn't help you do your job better?" Bob would reply that he's gotten by just fine for many years without knowing X, and he's been doing his job, so quid pro quo, ipso facto, ergo rectum, he obviously doesn't need to know X. He has no idea why you'd bother to ask such an inane question.