Comment by musicale

I don't consider stylistic imitation, or even outright copying or obvious copyright infringement, to be theft per se, since the original is not taken away.

But training automated systems on the works of human artists in order to create dirt cheap imitations at scale in their (formerly) distinctive style could certainly make it harder for active artists to find paid commissions.

Flooding the world with inferior imitations seems like it might have some negative consequences as well.