[JohnFen]

But that's entirely different. A digital artist is directly engaging in art. The computer is, in that case, just a tool like a paintbrush. The artist is still the one making all the creative decisions.

To go back to my ghost writer analogy, the reason that nobody would say I was the author is because I wasn't the one who made the creative decisions. I just described what I wanted to another person who made the creative decisions. Therefore, the other person is the author, not me.