Mine doesn't show any signs of being rear-ended, but who knows?

My thinking is that a warped pulley will set up a vibration in the belt
that, each revolution of the pulley, knocks the wp shaft and the bearing
inside in one direction only (toward the crankshaft) causing wear.

Also, the wp is so close to the main pulley that in-and-out variations might
not be absorbed by the belt, as they would be with the alternator, ac,  and
ps pump.