> If this is irrelevant, why is Stability.AI creating an "opt out" system for artists? It's almost like they know they are copying digital artists works without their explicit consent. This wouldn't be an issue if they only used images in the public domain.

It might also be because there's a huge backlash against the concept of stable diffusion in certain circles. Whether or not that backlash matches the legalities, or if their logic is sound at all, has absolutely nothing to do with it.