In addition to all of the other objections, the biggest failure here is of the technical measures to actually prevent copying. Even when it's prohibited by law and the pirates are a bunch of hobbyists, DRM gets broken time and again. You can imagine what would happen if copyright didn't exist and then breaking the DRM allowed for-profit businesses to legally distribute any of the content they extracted.

Copyright without DRM >>> DRM without copyright.

Though it should definitely be one or the other and not both. If copyright exists then DRM is not only useless, its existence is pure harm because all it adds to copyright is restricting things the copyright doesn't give the copyright holder a right to restrict, like free speech and fair use.

I like your point about DRM vs copyright. I guess I've always seen DRM as the "ounce of prevention" that replaces the "pound of cure" that copyright enforcement entails - although distribution platforms like YouTube increasingly reduce that pound to closer to an ounce (at the cost of more abuse). I think your point would be valid if enforcement of copyright was simpler and cheaper; perhaps you've read stories about photographers whose work has been used by large companies, without compensation, usually because the asset was included in projects done by 3rd party contractors. Its very expensive for an individual to enforce their rights. But yes, if the justice system itself were fixed to be fast, cheap, and fair, then I would agree that copyright alone would be the preferable solution.