I went through the post, and I am not sure whether I agree with the analysis of the examples. Diffusion models are conceptual parrots, and it is possible that "25% images contain a scribble in the bottom right corner, so the model will make a scribble in the corner" is what is being construed as a signature in this post.
I think a large part of outrage from the artists about diffusion model "stealing" art comes from a place of disbelief that machines can be this good without "stealing", and it's perfectly natural. In fact, it's unnatural to me how good machines have gotten in image generation, and it is a field I've been following for five years now. However, because I understand the model and can implement it myself, I can convince myself it doesn't need to steal, just needs to be able to model correlations at some ungodly level.