Can't think of the word or phrase to use, can anyone help me? Creativity isn't solely the domain of graphic designers? Something to do with prerogative?
Graphic designers don't have a monopoly on creativity.
I hear this most often with respect to truth: I'm told that Christians don't have a monopoly on truth, or something like that. It seems in that context to be effectively a claim to relativism.
(I've just noticed, after posting this, that the same phrase was suggested by someone above in a comment, but I'll leave it here since I came up with it independently, and since answers are, after all, supposed to be posted as answers.)
"Creativity isn't solely the province of graphic designers".