The "circle of life" except that it kills the artists' careers rather than creating new ones. Even fledgling ones might find that there's no opportunity for them because AIs are already gearing to take entry-level jobs. However efficient AI may be at replicating the work of artists, the same could be said of a photocopier, and we laws to define how those get to be used so that they don't undermine creators.

I get that AI output is not identical and its output doesn't go foul under existing laws, but the principles behind them are still important. Not only Culture but even AI itself will be lesser for it if human artists are not protected, because art AIs quickly degrade when AI art is fed back into it en masse.

Don't forget that the kind of AI we have doesn't do anything by itself. We don't have sentient machines, we have very elaborate auto-complete systems. It's not AI that is steamrolling artists, it's companies seeking to replace artists with AIs trained on their works that are threatening them. That can't be allowed.