There is such a thing as CD rot but it's not a widespread problem. A friend bought a bunch of CDs from the Koch label(I believe) that went bad. The company ended up replacing his for free as well as thousands of others. DVDs are actually worse because of the poorer dye that is used.
https://en.wikipedia.org/wiki/Compact_Disc_bronzing
https://en.wikipedia.org/wiki/Compact_Disc_bronzing