I think even if you had a dataset that'd only Creative Commons and public domain arts, you'd still have a lot of people whining. Because arguing that this is only about the dataset is disingenuous. This isn't only about the dataset. This is about the threat of automation and the extreme disruption of a status quo where artists are necessary for the production of large-scale media.

I honestly want to see datasets that are entirely Creative Commons, and a Stable Diffusion based on them. I personally suspect that not a lot would change. (Regardless, this is a moot point because training is now at the point where randos with a subscription to Google colab can easily create their own checkpoints. If you don't believe me, let me point you to the Furry diffusion server on Discord.)

Some online artists are really mad at the idea itself that people can "press a button and get a piece of art", and are trying to discredit the idea of "prompt-engineering" as a form of art. Even in videos like Steven Zapata's "End Of Art", he suggests that this should be a tool for traditional artists. The idea of individuals using this to create their own pieces (And worse, sell them!) is intolerable because it's inherently the intrusion of non-artists playing in the field of art.