Heterosexual sex isn't illegal, considered vile by society, mark you on online registries, prevent you from living in many places[1] or require preying and possibly kidnapping to accomplish. There are many reasons why a pedophile would watch CP but not actually attempt anything.

I'm sure there is a correlation, but I'd want evidence that it is high.

[1]: https://www.npr.org/templates/story/story.php?storyId=104150...