Maybe,but it has also proven effective in putting people who are not child molesters in prison for child porn. They should be helped,not criminalized - it's people who actually harm children who should be put in jail for the rest of their lives. And years ago you could only buy it from others - and that's why this technique of making possession illegal is so effective against drug dealers. If possession of drugs is a crime,then you can always demand to know who is the dealer, from the person doing cocaine or whatever. The problem is,that this doesn't really work against cp - sure, maybe 20 years ago when to get it you had to buy physical pictures from some guys in a back alley it made sense.
But what are you going to get nowadays? Hidden wiki's address? If you go on TOR there's tons of this stuff, and police cannot monitor it effectively,and cannot do anything about it, so it's unlikely that persecuting a person viewing this material is going to get them nearer the producer.
It also works against anonymous criminal networks, because the "turned" defendant can take actions that will result in the disclosure of the identity of the other anonymous participants. See: Sabu.
