Because they don't make blow up dolls that appear to be children (at least I hope NOT!)
These guys just can't get off on adult women. Their sexual desires are for children and their compulsions are strong. That's why I think the Seattle/LA guy who lives in his car and stalks little girls for pictures and claims he's violating no law needs to be stoned, hung or dropped off in the desert. Eventually his compulisve need will become so strong he will offend. We can no longer wait for that to happen and then try to explain our actions to the victim.
Jailhouse justice is the only chance we have.