There were a million Doom clones, none of which were as good as Doom. The same will be true of AI art copycats.
This, however, is not the first time ghibli has had competition https://en.wikipedia.org/wiki/Mary_and_the_Witch's_Flower in fact they have a whole studio dedicated to copying ghibli: https://en.wikipedia.org/wiki/Studio_Ponoc
Yes they used to work at ghibli, but so too did john romero work at id, and yet daikatana was not a quake-killer.
This doesn't devalue ghibli at all, I think
(In fact, I think AI will always have the fundamental problem that most people have no taste or sense or introspection, they don't know why good things are good, and can't see that crap things are crap, so they are predestined to only be able to produce garbage. Nod to Ted Sturgeon.)