Copyright does quite a lot more things than just enabling restrictions on distribution. There's the right to be credited, some limits on derivative works, and limitations to commercial violations. I suppose not every musician would be pleased to find their music used as the soundtrack of a porn movie without their knowledge, for example.
For example is someone took something I wrote and published it under his own name, that would be fraud.
Or if someone used my song for the soundtrack of a porn without making it clear that I wasn't involved, I would argue defamation because they led the public to believe that I was involved in pornography.
