> Obviously any artist producing fully original music or art doesn't.

I would suggest that artists who say they're producing fully original works are just poorly educated in art history. Making something that has no prior influences would be extraordinary in the modern world.

Also, the entities most capable of exploiting long copyright terms are corporations. Individuals simply don't have the resources to keep something relevant decade after decade save for a very small handful of exceptions like J.R.R. Tolkien.