The real culprits for the sharing of these sick images is modern technology and there is little we can do about that, but we can and should legislate just what is allowed to be posted to some of these poorly (almost non existant) moderated social media and networking sites. I think it a very sad thing the the authorities have to resort to making pleas like this to the public.
It's not just that, some of the newspaper sites were sharing the images as well.
Even the BBC site's standard blurb for information asks 'were you there, do you have pictures' (to paraphrase). Responsible news outlets wouldn't dream of showing the most disturbing images, but those who are more interested in the number of users on their site than actual responsible reporting will show them.
People have always been able to share images that have been taken by them, it's just now people can reach a wider audience instantly rather than passing physical photos or video footage around.
Modern technology is a great thing, there are more positives than negatives, but, like everything else, people can misuse it, and sadly, for those who chose to, there is an audience for it.