Just extrapolate the obvious into the future. When everyone can create good art, despite being actually completely unskilled and untalented, then good art ceases to exist.
When everyone's an artist no one's an artist. It doesn't matter if we're not there yet, we will get there eventually and at that point it's too late.
... not that it's stoppable anyway.
That is not what tools like this enable though? Will it not still require at least a bit of artistic sense to get something decent out of it? It just makes the technical aspect much easier. Some will benefit. Not everyone. Unless you're convinced there's a hidden artist in all of us?
It's just like with the introduction of small portable cameras decades ago (film/photo, doesn't matter) especially getting a lot better in the past decade: did we suddenly see great film/pictures being taken all over the place? No. We mainly saw a ton of crap, bad shots, bad home movies, you name it. And then some rather small fraction of people which earlier did not have the means to get quality material or were restricted in other ways, who got their hand on it and were able to deploy/discover their inherent talent. Which they could perhaps have done in other ways, but not as easy.
That's the nature of progress and art.
It's like arguing against grammar and spell checking, because "if everyone can write good texts, then good texts cease to exist".
Also, imagine what actually talented people can do with tools like this.
This AI art seems very menial to us, but not for the fresh minds.
This is same, and applies to our generation. When we were given tools to make art, our previous generations would have thought the same.