While it may be a beneficial term for cat food makers and cat food bowl manufacturers, whisker fatigue appears to be an actual diagnosis. When cats must eat from deep bowls and their whiskers rub against the sides, it can be a stressful experience. In turn, they may paw their food to the floor or become irritable during mealtimes.
Source: New York Times, June 5, 2017 (paywall).
Often, a regular plate will work just fine as an antidote to whisker fatigue, according to many cat owners.