> Because the copyright holder has granted you the right to look at paintings and hasn't granted you the right to store them on your server to perform the mathe

> Because the copyright holder has granted you the right to look at paintings and hasn't granted you the right to store them on your server to perform the mathematical transformations necessary to facilitate an adaptation-on-demand service. You just described how modern browser cache images. The diffusion model is revolutionary at scale, but doesn't mean it is doing anything drastically different than what is allowed right now, e.g. any AI based image beautifying/denoise filter, just the scale changes everything.