And yes, photoshopping your crush's face onto a naked body is just as unethical and immoral, even if done in the privacy of your own home, for the same reasons I mentioned above.
Compared to deep fakes, however, it has a much higher effort, lower reward, and less realism, which acts as its own inhibitor. Deep fake generators are becoming trivial to use, and not just for one or two pictures but for as many videos as you'd want. That's going to result in a very different driver of obsession.
Perhaps murder will one day be not very immoral, but that doesn’t mean we should treat it any differently today.
Right now, creating fake naked pictures and videos of real and non-consenting people is immoral. In some jurisdictions it’s illegal. It’s also probably harmful, by taking obsessions further than mere imagination would allow.
The reasons you mentioned above were "it feels more real than imagination" and "a person could go back to it over and over, enhancing their obsession with the non-consenting person". These are not moral bads that require a "no lusting after people, even in your heart" style rule. Being obsessed with people starts in high school and can persist for decades. They never find out, and it never hurts them.
I'm sure many people would like to take away others' ability to picture them naked, but fortunately they didn't have the ability to enforce that by starting a moral crusade against a Github repo. It's one of life's innocent little pleasures.
It's immoral because it's creating something persistent that could harm someone without their consent, amongst other things.
I also question your assertion that obsessions of this type are always harmless, because it's obvious that many are not and escalate into outright stalking, confrontations, or worse, and anything that makes that sort of obsession more likely or helps to enhance it where it exists increases the chances of that happening.
Yes, and it's already widely considered to be really fucking weird behavior
Of course it took years for me to perfect my artistic skill in the area of erotic fingernail sculptures and by that time anyone could afford a Photoshop license.
I agree with the person you're replying to, you can't stop people doing these things in the privacy of their own home and these deepfakes are functionally similar to other photo / video editing techniques.
_Distributing_ those photoshops / deepfakes is another thing entirely though, and one I am fully against.