I have noticed this before, but today when I went to get some feet for my newly built boat stand I was amazed/astonished/appalled by how bad it had got.
I have some of those multidrawer storage things with plastic drawers for bits and bobs. This one has a load of grey 'rubber' feet in it. They have somehow reacted with the plastic of the drawer so as to impress themselves into it. This has taken place over probably 10 years or more.

I've had similar with black grommets too. The really strange thing, to me, is that the actual grey feet seem unaffected. They have to be pulled off the plastic as they are quite stuck, but once freed there is no sign of damage to them - only the plastic drawer.
Years ago I painted over some domestic wiring cables (PVC sheathed) with (vinyl) emulsion, and found that the paint never fully set - for years it remained a little sticky. I guess that the vinyl of the paint and the vinyl in the PVC were somehow interacting. So is this business with the drawer something similar?