> The only thing I can see people worry about is someone putting a real person's face on a porn image. But deepfakes are also around for years and we don't really care or affected that much. Why bother with what people do behind closed doors? As long as they don't harm anyone, what they do in private is their own business.

The problem is when it doesn't stay behind closed doors, but instead when this is used to harass the person being depicted. Non-consensual distribution of porn is a big deal because there is a lot of evidence of its harms, including a very large fraction of people with suicide ideation.