I agree with pretty much everything you have to say in here. I didn't miss his point though, if he said there are a lot of factors in shootings and violent societal outlets are some of the factors then I might agree, but he didn't put it that way. Your comment about outlets is key. Parents use the television as a 24/7 babysitter, and if parents do take their kids out to dinner then it seems like immediately they give them their phone or ipad to watch something on instead of interacting. It's very necessary I think to have outlets, concerts were mine, riding bikes, etc. But if your face is in the television all day and all night then yes something mentally is probably going to snap.
What's funny is the video games and music always gets the shaft when it comes to blame but you don't really hear about television and movies. If a kid isn't playing video games then damn near every show and/or movie you can watch has violence (Iron Man, Captain America, anyone?). But we should all focus on video games though.
In the end, it all comes down to parenting. Almost every excuse one could think of (even Nate's very valid mentally unstable comments) comes down to parenting.