It absolutely is. I see plenty of AI art used to illustrate websites that would previously have used stock imagery for which someone got paid, even if only a small amount. Even in contexts where it is used as a free gift (ie adding AI art to social media posts that would have just been text before), it has the function of crowding out human made art by its very proliferation. It's like Greshams law for media files.

https://en.wikipedia.org/wiki/Gresham%27s_law