This so called study is hogwash.
It's not a study, it's an opinionated observation. There are so many things left out and unobserved, that to call this a study is an insult on anyone who is educated.
People do what they do based on opportunity, knowledge of something and whether or not it's 'cool' vs responsibility/irresponsibility.
In the 70s kids did one thing, in the 80s another and so on. To attribute it to one main thing or another is ridiculous.
Also, these horrible tragedies whether they involve kids, college campuses, alley ways, belt ways, etc. have been going on for many decades. The only thing which changes is the number of people who are made aware of it.
Today, EVERYTHING makes national if not international news. The Watts riots in the 60s didn't make the news in London, and its significance didn't even make it to Orlando. Today, it would be an entirely different story.
...and then there of course is ignorance. What people are told, because it's easy to sell them on... or it's what they've been led to believe. Especially if they don't have any idea at all. Such as the right to own firearms. There is no 'gun culture' in America the way people are led to believe it in Europe. Gun use comes down to the same thing nearly everything else does... responsibility or irresponsibility which is mainly placed on us by our community. Not a video game, music, etc.