I’m hesitant to jump in with both feet about gaming, as I know little about it, and a quick search on Google Scholar didn’t throw up much. My children had a PlayStation and when they were young I restricted their games to ones where there was no killing, so they collected carrots or raced around in cars and so on. This was easy until about the age of 12, when it became increasingly difficult to find games that stretched them but didn’t involve killing at some level, other than FIFA and similar sport-based ones. The fact that gamers are actually doing the killing as opposed to watching it seems dangerous to me, yet studies I read at the time seemed to suggest that gaming encouraged cooperation and strategic thinking (but I was looking more at reports of the findings than at studies themselves, which is notoriously unreliable). Luckily neither of them were remotely obsessive gamers (and neither plays now on streamed games which were not around when they were young) so it was just part of a broad range of activities that they enjoyed.
The risk of the obsession and isolation that some children succumb to was another of the worries that I didn’t have to face (along with the worst excesses of social media exposure), and I don’t know how I would handle it if I had young children now. A friend’s son is worryingly (to me) obsessed with gaming, and in his late 20s spends hours in his room playing online late into the night. It seems such a waste of his youth, but it obviously gives him something that I don’t understand. I do think that the potential for danger inherent in dealing so much with people you don’t know, (and in the killing side of it) is there, but then I am on here most days, so am maybe not in a position to talk 🤷♀️
I don’t think that too much gaming is at all healthy for social development, but neither do I think it is responsible for the killings we are discussing. It may encourage a detachment from the reality of violence but probably (as with tv and film) only in those who are already susceptible to that influence.