You might be philosophically right but I assure you that I would have to hire a large group of professionals from all directions to build an house because I'm absolutely incapable of building one myself. The right people for the right job! Also it might be a little forced since the writer and the painter would surely had a mentor that teach them the art that then they developed in their own way and in many cases they overcome their teacher if they were good students. The creation was theirs but they might have "consulted" with their own mentor about the techniques and materials to use to materialize that creation after it came to their mind.

Man, you are confusing authority with authorship.

I don't understand this act as an appeal to authority, as it proposes to be, like someone validating nonsense using their titles instead of facts. Next, I understood your concept and why you used this term. It's not a case of appeal to authority, as @javier said. That's why I think few people responded focused on that term.

You made yourself clear here. Consulting someone would make your unique work become a joint effort, and in case that person has more experience or titles, it would be considered their work. Even if it was to avoid issues, your piece would end up being conditioned to not being solely yours.

I'm glad that my question led to further clarifications on points that can sometimes seem obvious, like the authorship of a work.