The roman Empire had graffiti. Also a sorta hybrid between graffiti and advertising.
In Pompeii, they found a house exterior wall that said,"Cave canem!" = Beware of the dog.
While I am sure Tron and GoG is partly from people picking at it,I also suspect some of the damage is also caused by people simply rubbing up against it. WhenI first saw the peeling on GoG, I had similar thought to those expressed on the first page of this thread.
On a repeat visit, GoG went down, and we spent an hour not moving. Many people sat down, with their back against the walls, and suddenly the damage made more sense. In Tron, we saw people rubbing the walls as they went through. I'm not saying it is something people should do, just that some of the damage is wear and tear. WDW should use more durable wall coverings.