The problem with nightshade or similar tools is, that if you leave the changes it makes at too weak a setting, then it can be pretty easily removed. For example GAN upscalers that pre date modern "AI", were pretty much built to remove noise or foreign patterns. And if you make the changes strong enough that they can't be removed by these models (because so much information was lost), then the image looks like shit. Its really difficult to strike a balance here.

Read it. I don't think it will have bigger impact than lossy image compression or noisy raytraced images.

If it can be added programatically it can be removed programatically. It's bullshit.