Ah, but the metallic backing on the OEM CDs degrades as well, and then the physical pits and lands cannot be read correctly anymore, either. Read an article years ago where they left an OEM CD exposed to direct sunlight for some time and it was unplayable afterwards. The gist was that the corrosion of the backlayer was a significant limiting factor for CDs.
I remember when CDs first were introduced. Most folks thought that properly cared for, they would last forever. Sadly, they proved to be susceptible to scratching if not handled with care, and if severely mishandled this scratching could cause it to fail to read.
I still have the very first CD I ever purchased, (Dark Side of the Moon) and it plays fine. In fact, I just ripped it using cdparanoia, and it didn't show any errors at all. From my own experience, later CDs were more susceptible to environmental factors. Seems they originally started making the darn things too well and people weren't having to re-buy their albums. The evil bastards in the music industry hate that kind of performance with a passion.