Child porn is an excuse. Every site above a certain size will have some, no matter how good their filtering. And sometimes even small sites when they come under attack. Then whoever wants to get rid of the site for unrelated reasons points to it, says "It has child porn", and no matter how quickly it is removed after reported, or how much effort the admins spend removing it, "it has child porn" is technically true, and gives whoever wanted to remove the site the excuse to do so.

It's nothing more than ammo that corporations use against each other in the fight for dominance, or sometimes, with the help of cooperative media, against politically disfavored sites like 4chan. In all my time browsing 4chan, I have not once seen child porn, though I did see posts 404'd for having contained child porn. Yet despite their efforts, any time the media talks about 4chan, they will introduce it in the same breath as child porn.

In short, child porn has become nothing but a tool for corporations fighting for dominance, or a fnord to tell the masses to stay away. And in all of this no-one gives a crap about the children, since they rarely spend even a word talking about tracking down the uploaders or creators of said porn (i.e. they say a site "has child porn", but not how fast it is removed, or if the site gives the IP of child-porn uploaders to the police, or anything beyond trying to establish in the viewer a bad site <-> child porn association).