4chan doesn't do anything illegal unless you think that being mean should be banned.
It's just as irrelevant.
"Police drag away a man for saying he likes bacon near a sprawling mosque construction site" (https://www.wndnewscenter.org/we-like-bacon-man-arrested-for...)
There are no drawn or otherwise images on 4chan that are illegal under United States law.
The UK is actually criminally investigating anime artwork websites and raiding people for how lines and shapes are drawn.