As I’ve moved a few times, gotten married etc., I’ve thrown out a LOT of old textbooks, novels and papers. They weren’t worth hauling around or storing. But I still have most of my old electronic documents from back then. Complete with off-site backups.
There’s also the ability to make copies. A year ago one of my co-workers had his house burn down. He lost his collection of electronics books, magazines and manuals.
I had been collecting them off Usenet and other sources for a long time and was able to run off a copy for him - thousands of books, magazines and manuals - on several DVD ROMs. Which in turn he’ll have copied to a hard drive, and made backups of.