"""I also don't see any involvement of the internet in such dramatic and frightening cases as the child sex abuse in Rotherham."""
The authorities and the establishment are keeping it quiet.
The gamergate exploded because the people involved had first hand knowledge of what was going on. So when the game journos tried to accuse their critics of being misogynistic & racist, etc it exploded in their faces, and rather than trying to keep it quiet, they went on and on, eventually more and more people woke up to it.
In the case of Rotherham no one is talking up because this is not just some "kids stuff" thing, this is a very serious societal problem that has been allowed to happen in purpose, those responsible for letting it happen (hint politicians and their advisors) keep and force a low profile, lest the British public question the status QUO.
See establishments like the BBC or the government have invested so much in certain "cultural" themes that they can not walk down on them without looking like complete idiots.