Copyright law still benefits people.
Overall it does. In some specific situations, it does not. One category of these is a copyright owner deliberately keeping a previously published or publicly exhibited work out of print everywhere or in particular countries. An example of this is Song of the South. Another is uncertainty over whether a song you've written is legally original, as opposed to an accidental infringement of copyright in someone else's song. An example of this is "My Sweet Lord" by George Harrison. Why are those specific cases worth keeping?
Heck, I did something similar with a needle - just pierce a hole at random, then figure out which sectors are unreadable in my original. If you could read them, the floppy was not an original. And since it was at random, no two disks were alike. Writing data to the original wasn't a big deal - once you knew where the bad sectors were, skip over them.
Nintendo GameCube disc authentication works the same way: burn six evenly spaced pinholes in the lead-in at some random theta, and then mark in the Burst Cutting Area which sectors were burned.