Your point is starkly true and very sad. There is a big difference in both societies. HK is a wealthy area and fairly tech advanced, so many people have cellphones. I think the yazidis live in under served areas from a tech/internet perspective. Somehow I'm hoping that makes a difference.
my point was that the yazidis had smartphones, and there is plenty of footage. It has not become mainstream for some reason.
Heck, TODAY, the army of a nato member is slaughtering civilians in northern Syria in plain sight. There's ample footage of the killings and it is horrific (e.g. tanks marching over people, including women). It gets systematically banned from the main social sites.