The problem with that logic is that there is no actual proof of it. For example, there is no proof at all that playing a shit load of violent video games will turn you into a murderer, or even make you more violent/aggressive in your general life. And the links between video games and violence are the most studied example of this we have. I refuse to believe that looking at a cartoon will make you a pedo rapist just as much as I refuse to believe that playing call of duty will make you a murderer. If you are willing to cross that line, there is something else much more fundamentally wrong with you, as normal people can tell the difference between fiction and real life.May I advance a theory of mine that's relevant to this?
I believe that sublimation is ultimately a bad thing.
The usual defense for stuff like loli and violent vidya is that it's sublimation, allowing for the individual to satisfy their need for something without doing the real thing.
The problem is that it's generally known that the more you indulge something, the more your appetite grows for it. In the case of sublimation, the more you sublimate your desire, the more you want to. In a small enough amount it may not matter, just like how most people's appetites have an equilibrium. However, many people have a tendency to go beyond that (get addicted), and some things especially lend themselves to that.
In that case, the more you sublimate, the more you need to sublimate, and eventually it gets to the point where the sublimation no longer satisfies and you need the real thing. The classic, if admittedly contestable, example is Ted Bundy, who claimed that his addiction to violent porn gradually spiraled out of control until he started committing actual murder-rape.
The best way to reduce a bad behavior caused a bad thought is, sheeeeit, DON'T THINK ABOUT IT. Repression isn't good but indulgence isn't either.
TLDR: Wacking your gack to little girl cartoons will make you want to whack it even more, and eventually it won't be enough and you'll want to rape the real thing.