Traditional companies lead with fear of losing ownership. If someone’s making money selling t-shirts with Mickey on it, that is money Disney’s losing - direct value attribution.
CC0 is essentially LEGO for ideas - composable IP. Why? Cuz memes run people’s minds. Releasing IP into public domain increases points of discovery, and enables anyone to build upon it; i.e more cool stuff and more people interacting with it - indirect value attribution.
The result? With monopoly power gone, creators will compete on quality and creativity of experience they provide. In other words: more people wearing Mickey shirts ⇒ more ppl thinking about Mickey ⇒ more potential for building on top of Mickey.