The argument is that for something to be "stolen" it has to be missing afterwards. An unauthorized copy is copyright infringement, legally speaking, not theft.
Words mean something and there is a reason why right holders tried to coin this (pillaging, murdering) piracy to give it a bad connotation. Then the various "pirate parties" said if you want to call large swaths of the population pirates, then we will be taking that word from you (somewhat similar to pride movements).
The courts ruled on this last century. At least as far back as the 80's when people were stealing HBO from satellites with TVRO dishes in their backyard.