You might be fine with having erotic materials made of your likeness, and maybe even of your partners, parents, and children. But shouldn’t they have right not to be objectified as wank material?
I partly agree with you though, it’s interesting that making an image is so much more troubling than having a fantasy of them. My thinking is that it is external, real, and thus more permanent even if it wouldn’t be saved, lost, hacked, sold, used for defamation and/or just shared.