violent video games are certainly not the reason people go on shooting sprees. There obviously mental health issues as well as possible personal trauma that are the main reasons.
That being said, it isn’t like there isn’t a correlation. Most of these shooters are drawn to violent video games and they can help dehumanize and desensitize the idea of a real life massacre. However, these people have to already be ill or unhinged.
Honestly, if congress really wants to curb these mass shootings, the most effective thing they could probably do is outlaw news coverage of them. That would be far more effective than getting rid of violent media. If a shooter knew they wouldn’t get their 10 seconds of fame, these events would be much more rare.
Unless you want to close off mass shooting areas more tightly than Chelyabinsk in Russia, ain't gonna happen. Most of these shooters would just settle for terrorizing the local community, in any case, and that's something you really can't hide from the media. Keeping stuff like this off the media will not help. They'd get plenty of play on social media and message boards just from viral word of mouth, and the Streisand fact might very well amplify it beyond anything the media could do on its own.