I mean, it is a country of laws. Just...some of those laws are pretty bad. For what it's worth, the Court in this case is narrowly focused on correcting a lower court's interpretation of the Copyright Act, not something in the Constitution or something fundamental, and on a first glance, I at least feel that their conclusion is highly justifiable. That doesn't mean the Copyright Act isn't fundamentally broken (it is, on my opinion), but that's trivially fixable by Congress if we get appropriately minded representatives.
The doctrine of adverse possession is well-established, at some point there has to be certainty about who owns what. Look at East Germany after reunification if you don't believe, the fights over real estate seriously delayed rebuilding.
But for copyright adverse possession doesn't apply - it's understandable why the music industry would have the Court say so.
