I feel like at this point they are trying to find excuses for the mass shootings rather than tackling the main cause of the issues. Nine times out of ten the people who take out these shootings end up having some kind of mental health issue, many of them probably don't even play video games. Bill Clinton once banned assault rifles and mass shootings dropped dramatically, George Bush allowed them again and they increased again. What needs to happen is gun laws need changing and more help needs to be given to those who suffer with mental health, people need to realise mental health is nothing to be ashamed of and they need to speak up if they need help.
This goes extremely deep though, and it is by no means the only cause. Often you find people "accidentally" shooting someone or having a gun go off because they got spooked. While on a smaller scale, these contribute to the bigger issue at hand. Rather than trying to get to the root of "why do people feel the need to shoot a bunch of people", why not try to get to the root of "why do people need guns"? Weapons exists for a single purpose, to react to situation. The situation that (in this case) America is so proud to announce is the "I need to be able to protect myself" which stems for the emotion of distrust and deep-seeded hatred towards other people.
In a world where people think about their own place in the world, rather than the place of mankind in the flow of time, reasons like this will exist. People "need" to "protect" themselves because they don't trust their friends, their neighbor, a stranger across the street. So while I am all for dealing with mental issues when they are the cause, they are by no means the only cause and I'd personally use my time to foster a healthy society rather than trying to force my opinions on others about mental disorder. If people didn't distrust and hated each other, bullying would be almost non-existent and as a result that would solve a large margin of not only people that commit mass shooting as a result of it, but also suicide rate.
Though I do agree with you, blaming something like games for tendencies that are usually brought on by people is nothing but an excuse. It's almost as if people are aware of their own fault in it, but because they don't wanna own up to it they blame stuff like games, race or religion.