1) When artists 'steal' from others, they generally build something 'new'. AI can't really create anything 'new'. Case in point: Umberto Eco's The Name Of The Rose steals the plot and outline from crime stories, steals the library idea from Borges, and steals the murderer's motive from Eco's medieval manuscript (forgot which one). Yet the outcome is something completely new. Same goes for hip-hop music; sampling is at its core, but the final music that comes out is nothing like what it samples, the samples are just a part of something new.
2) when artists steal from each other, it's generally poor artists ripping off other poor artists. No money can flow. When a million/billion-dollar company rips off poor artists to make more money via generative AI it's a different story. Money could flow but it doesn't.