We don't need DRM to enforce reselling. Equipment and methods to reproduce physical media are widespread today and there isn't a way to prevent copying and then reselling. Other than the marginal cost of CDs, Vinyl, cassettes, etc.

Purely digital just drops that cost from a few cents to nothing. DRM free music stores have existed for over a decade and already de-facto operate in this manner.

There isn't a practical reason to require DRM in order to have ownership over a digital copy of a song.