What do copyright laws (which, don't get me wrong, have a whole kettle of issues for sure) have to do with this?
DRM is just a thing that authors choose to put into their media. The fact that they do it because enforcing copyright via legal channels is unrealistic is effectively incidental.
If anything, what is necessary to achieve the objective is putting limits on what authors are allowed to put inside of the media they are producing, which is a heck of a can of worms in of itself that I think zealous preservation advocates are a bit too eager to brush off.