It doesn't prevent it. It does make it very hard to produce it for commercial reasons, though. This means little is produced simply from commercial motives.
So your argument is to prevent the harm involved in the production and supply of graphic materials, we should cut out the demand for them. Is that correct?
I'm not saying right or wrong, but rather simply why the law is the way it is. Whether it is a net benefit to society or not I do not know.
What you are showing is the harm caused by witch-hunting about child pornography. In the quest to stamp it out they sweep up lots of things like the images you refer to which are not pornography.
You can dismiss it as "witch-hunting about child pornography," but the effort to destroy images deemed pornographic of children is part of such censorship, and it threatened an innocent mother. As I see it, the laws against child pornography are the product of prudes and politicians who can't even define what they outlaw.
You miss my point--I'm calling it witch-hunting because they're going after stuff that isn't pornography.
So, a few things here. One is that child porn must not exist, especially realistic porn, because there is a vested interest in preventing the exposure of people in sexually compromised ways against their consent.
Much like the release of revenge porn being a violation, child porn is an even worse violation, and this violation almost universally happens at a time when consent cannot happen.
I will advocate till I'm blue in the face to draw, or have an AI draw whatever you want, especially if you have the AI model hash and seed to prove it came from a computer...
As soon as we start talking about things like images of actual children or images of unknown and questionable provenance, all that has to be torn down. Ideally the very economic factors that encourage it should be torn down too, as such images are violations.
I will note I have hedged some statements here. It is technically possible for a kid to snap some pictures of themselves, hold onto them in private until they are no longer a kid, and then make a decision on whether they feel violated by them, but the rarity of that event moots the point in that for every molecule of ethical material there is a practical moon of evil material, and to find that molecule you have to accept the existence of the other.
As a result the only ethical material to keep, display, etc of that type is stuff that is clearly "pure fantasy": drawn, CG, and AI art, posted in places restricted to adults.
It's absolutely the case that witch hunts happen. I can't tell you the number of awful events where someone is doing everything right, sticking to adult websites and sticking to ethically produced images, yet still get stormed by 17-21 year olds on Twitter for being "pedos", especially artists, when the whole point of all that work is to NOT have that issue.
The problem here is that purity is seen as a virtue, when purity is not in any way virtuous, a clear failing of the paradigm of virtue ethics in general.
The overall result of such crusades is popular art sites not just saying "have an account, be 18+, and explicitly opt in to seeing that content, and tag it for what it is" but wholesale banning it and anyone who draws it from their site.
Even IF it is pornography, even if the things in it look like children, if we can validate that those events and children do not exist, and if we can keep children from accessing those images, and if we can make access to new images completely free of any need to violate the sexual privacy of anyone (through manual or generative art), I just don't see the problem with it.
To that end, I am even more interested in the average party to see actual CSAM completely stricken from the internet, and to see violators of tagging policies dealt with harshly and swiftly.
There is a whole community of age players built specifically so people could both have their interests and engage in them ethically, and censorship is important to that, in keeping us protected from the intrusion of predators and creeps.
TL;DR: censorship protects people who ethically consume pornographic drawn and generative art of themselves and aspects of themselves and other consenting participants in fantasy situations from the exposure to evil acts, people who knowingly have contact with or who are themselves child molesters, child abductors, child rapists, and child murderers.