Why does that matter?
"Got a gentleman's sweep in the ECF at the age of 22" isn't the measure of a player. Rose relied primarily on his athleticism, he was already close to his peak at 22. Westbrook was no different, he was scoring 43 in a Finals game at 22. Curry took longer to peak especially due to the nagging injuries early in his career (though like I pointed out he outplayed Rose head-to-head more often than not), but a later peak don't mean a lesser one.
Kiki Vandeweghe and Kelly Tripucka were 25-30ppg players at the age of 23, so I guess they were greater than Larry Bird and Dirk who took slightly longer to peak.