As a human artist, I can study Picasso's paintings my whole life and paint in the style of Picasso, but as long as I don't copy an existing work of Picasso then how can what I do be copyright infringement?
Copyright doesn't protect style, afaik, though IANAL.
Incidentally, human artists get copied all the time. Walk outside any major museum and you'll see endless Van Gogh imitators peddling their wares on the sidewalk. Somehow people don't get all hot and bothered about it. But when an AI does it suddenly everyone's up in arms over copyright violation.
How many human artists have copied Picasso's style? Probably thousands. How many have tried to paint like Da Vinci? Probably millions. Where is the outrage?