In the realm of art we all borrow. This is not a sin. The problems is AI art is it was unnecessary and makes one circumspect about what it means to be. Purpose and all that.
Give the humans their little past times. Why farm that out to a machine. Art is about feeling and I think we see that the AI evokes feeling in us and we are bothered by that. Some say it’s the borrowing of images - but I find this dubious at best. All art builds on previous and sometimes someone breaks free and really flies.