It depends how very young the kid is. Sure, let's say- a 5 year old watches a violent scene on TV. He probably knows when someone is hurt, and may not yet understand that people on the screen aren't real, and the recording of it isn't real either.
Let's actually start talking about adults. If a grown man sees a real life equivalent of carnage in a normal shooter, he would go insane. Soldier in his lifetime kills less people than a kid in a single game.
Violence affects everyone, regardless of age. However we can distinguish reality from fiction.
We had books, paintings, plays, movies, and now games. None of those mediums warped our minds, made us sick. That's because they affect 2 senses at most. We KNOW that they aren't real because at the moment of watching/reading we sit in a comfortable position, in our houses, where nothing is wrong, not FEELING anything outside what we IMAGINE.
Imagine the different levels of immersion:
I- A kid is told that in World War II died over 60 million people. Kid doesn't give a damn, those are just numbers. Why not billions? Those are bigger.
II- Kid is shown pictures from the war, all the dead bodies, crying mothers, sheer ruin and destruction. Kids uses his imagination and yeah, that would suck, being there.
III- Kid goes to a place that had been ravaged by war a long time ago. Marks still remain, that black mark on the wall? It was a person who got burned alive. Chills run down the spine. A real life ghost story.
IV- Kid goes to war. Sees soldiers raping women, killing children, houses burning, sheer madness and destruction of war. If he survives, he won't need an explanation, why war is bad. He will know it, feel it.
I had the same reaction when told about the war. Seriously, millions dead in numbers didn't make an impression on me, but hearing of decapitation, rape and piles of dead bodies of a thousand civilians in a single village? That I still remember.
Sorry for the rant but seriously: reality is reality, fiction is fiction, we know the difference, and kids know that too.
Taking it away without anything in exchange is not going to make thins better. Sure we know that stuff is needed, but it's not enough. It's going to keep some parents at bay, but kids? They won't really know why it would be bad for them.
We need to talk about that, just like smoking or drinking- it's bad for you, especially when you are under 18, but if no one bother to explain the effects of it on you body and mind, you are going to try it out of sheer curiosity, or preference, or rebellion or anything really.
Bad stuff is out there, in the world. Not outside the border, in some 3rd world country, but here in our neighborhoods. Kids will bump into that when they go to school, or into their friends houses. They will interact with that like it's airborne. If they won't protect themselves, then no one will, no one will be able to.