Stevens was a lousy judge appointed by an unelected, inexperienced, nieve, happy guy president (Ford) who could’nt even walk on stairs without falling on his ass. How the decision to put Stevens on the court was reached we will probably never know, but we do know it was a hell of a mistake.
Kavanaugh’s strident defense at the kangaroo hearing rocked the Left back on its heels. They had never been counterattacked in that manner, and such tactics make it virtually impossible to get away with their smears.
Thus they are trying to establish a new rule. Defending yourself stridently shows that you lack judicial temperament, and are hence ineligible for the Court.
See how that works?