Consider Netflix: even if you technically can share & adapt movies or binaries without any problems, there is still a profit incentive to make them very hard to acquire, hidden behind an effective DRM. I'd say security through obscurity, even if minor, is large enough of an incentive to not make your DRM source code freely available.

CC: @eric@pl.starnix.network @Suiseiseki@freesoftwareextremist.com @maija@netzsphaere.xyz