There's nothing stopping the same thing happening to HN, except the people that do it have no interest in doing so (and images don't auto-display, I guess).
They're all behind variable IP VPNs. Permanently getting rid of them is nearly impossible.
8chan deliberately set itself up such that it's impossible to do anything beyond an IP ban. This was a conscious choice they made, and that doesn't mean they get a pass on failure to enforce rules as a result.
By making a transaction (or series of transactions) that happen to have a binary representation (or destination address, or comment, or...) that decodes to CP - the same way that you'd store any other arbitrary data there.
The 8ch.net/delicious/ board routinely had extremely realistic animated images and video of prepubescent girls having sex with older men. The images were reported to mods who left them up.
That's the sort of thing that starts to hit some really grey areas, and also starts to illuminate some of the differences in the justifications for banning CP. If you're against CP because it means the exploitation of children, animated images of children that do not exist should be fine - but if you're against it due to it being disgusting or normalizing the abuse of real children it's not. However, I believe that the Supreme Court has thus far held that drawings fall under the 1st Amendment, as (IMO) they most certainly should.
There is an important shade of grey between "clearly artificial image" and "real image", where "artificial but real-looking image" sits. It has the same normalizing effect as a real image.
Otherwise there's no reason to oppose real images, since the harm is done before the image is ever seen.
> Otherwise there's no reason to oppose real images, since the harm is done before the image is ever seen.
We ban specifically real images for two general reasons - one is that allowing them encourages the production of more such images, necessitating additional abuse, and the second is that for the children involved, knowing that other people are looking at those images is a huge violation.
Neither of those applies for "artificial but real-looking" images.
Fun fact, there are places in the Western world where it is considered illegal to the same degree as photographs of children being abused. And ditto for textual descriptions of this fictionally happening. Scandinavia, for instance. Which is admittedly not famous for its uncompromising approach to freedom of expression.