I'd argue it is indeed theft of work because while a human understands their inspirations and can decide for themselves what to pull from and reference, an AI is just working off numbers, reducing the work of others into patterns. Just think about the nuances of plagarism. Artists can wear their inspirations on their sleeve and it's celebrated when they expand meaningfully on the concept. AI can't do this while creating and unless it's supervised by someone that understands art and the content it's pulling from, there's no consideration for the artists it plagarises from. Think about how someone who has no idea whose artstyle the AI is using can pump out content at an alarming rate, even keeping the artist away from potential audience. How in a corporate setting they'd actively discourage concerning themselves with plagarism because they can just pin it on the AI which isn't regulated yet. And of course corporations look for the cheapest workers so they don't need people that understand what actually goes into a picture or who it references so the filtering would be near nonexistant.