The cable is one of 4 for our 1st electric. 2 of the cables are rubbing, 2 are not. I was actually surprised as well that the plate would wear so much quicker than the cable its self.
Not sure which is worse here - the guy who installed it so that it rubbed, or everyone who's seen it rubbing over the years and not addressed it...
I'd lean extremely heavily towards replacing the cables, and figuring out why they're rubbing.
A building here in my town used to have multi-sheave diagonal head blocks, with the short line of the first electric pulled over at a 20+ degree fleet angle, sawing through the frame of the head block. Fortunately, it finally got rerigged before anything bad happened.