This commentator points out very convincingly why the US Navy can never expose its main carrier groups in a conflict with nations like China or Iran, because it means they'll all lose their jobs.
Which means they can't be used the way they're intended. Which means they are enormous, expensive floating boondoggles that keep no one safe and will win no wars.
It isn't until engagement with the enemy that you find out whether your plans and technology really work. By avoiding that crucial confrontation we don't validate our strategies and tactics, and refine them for future conflicts.
Not that THAT is such a bad thing; it would definitely suit me if we never find out whether the carrier groups still have legitimate military value. But you could get rid of them entirely and still know just as much about their usefulness...