The reason it's illegal to distribute and possess CSAM is, to my knowledge, not to mitigate demand for its production, but specifically because we have every indication that its distribution (really, knowledge of its distribution) does inflict subjective harm on the victims.
The reason anything is illegal is because of the subjective experience of perceived harm. There is no harm that exists other than the "subjective", "experienced", and "perceived" kind. The question is just whether the rest of society empathizes enough with that harm to protect against it.
I do find the argument around allowing (fully) synthetically produced imagery in order to satiate demand for CSAM without harming real people an interesting one. I'm not sure where I land but probably probably somewhere near "if it actually reduces demand for harm-producing imagery, then good, and if it does not reduce that demand, then bad." I.e. this position would probably increase everyone's chances of coming across synthetic CSAM which in turn might actually increase the market for "authentic" material. Not sure how this would play out.
The reason anything is illegal is because of the subjective experience of perceived harm. There is no harm that exists other than the "subjective", "experienced", and "perceived" kind. The question is just whether the rest of society empathizes enough with that harm to protect against it.
I do find the argument around allowing (fully) synthetically produced imagery in order to satiate demand for CSAM without harming real people an interesting one. I'm not sure where I land but probably probably somewhere near "if it actually reduces demand for harm-producing imagery, then good, and if it does not reduce that demand, then bad." I.e. this position would probably increase everyone's chances of coming across synthetic CSAM which in turn might actually increase the market for "authentic" material. Not sure how this would play out.