IP theft doesn't exist, if I copy a Disney movie, Disney still has their movies. If I steal someone's bike, they can't use their bike. You deprive Disney of nothing by "stealing" their movies since it is just a copy.
Maybe you are correct that there is no such thing. But that is a different argument. In the U.S., from a practical and business standpoint, IP theft does exist because there are laws that are passed to prevent it and enforce consequences.
Disney is not just selling tickets to movies to make their money. They are selling licenses that provide the rights to watch, store, and use those movies (or aspects of them) in certain ways. One thing that that Anthropic didn't do is pay the publishers and authors for the right to train their models on the intellectual property. And that's why they have no place pointing fingers at Alibaba saying that they stole their IP.