Aiding authors is an instrumental, not fundamental, purpose of copyright in the US; the fundamental purpose to which any instrumental purposes are subordinate is “to promote the progress of science and useful arts”.

That is, while copyrights are a form of property, they are not something that is seen as natural property, but instead property explicitly granted as a means of achieving a public policy goal, and therefore limitations (or even elimination) harming the owners of that property is not the kind of dispositive argument against a policy that would be with the kinds of property seen as natural property.