I've always been confused about this train of thought, because it seems to justify the opposite of what it's trying to say.
I mean, if the argument is people will use whatever garbage they have on hand to make art... presumably that includes generative AI? Look, I lived through four decades of people making art out of ASCII. My bar for acceptance for this stuff is really low. You give people a thing that makes pictures in any way and you'll get a) pictures of dicks and b) pictures of other things.
I don't think GenAI will kill human art for the same reasons I don't think AI art is even in competition with human art. I may be moved or impressed by a generated image, but it'll be for different reasons and in different scales than I'm... eh... moved and impressed by hot dragon rock lady here. Just like I can be impressed by the artistry in a photo but not for the same reasons I'm impressed by an oil painting. Different media, different forms of expression, different skill sets.