There are thousands of images of real murder[1] and other absolutely heinous acts committed against humans and animals out there. Millions and millions of murder fiction books purchased every year. So much violence in the media. And people with secret obsessive interests and fantasies of torture and homicide, who view large numbers of such images intentionally. And a large number of homicides each year.
We do not prosecute people for looking at images of murder on the Internet.
So comparatively little is done to stop that, instead we focus on sex-related moral panics, driven by what is likely a primitive primal human instinct.
1. War crimes, etc.