I grew up without any censorship (and I mean any) but I had responsible parents, who were willing to answer all my questions (including the ones people shy away from answering for children) and I turned out ok, no crazy delusions about anything, not crazy violent, etc.
If people are responsible and teach their children instead of sheltering them from literally everything, the kind of content you intake (violent, sexual, etc) is not damaging, it's simply exposure.
Keeping people from experiencing something and simply telling them its bad is not going to keep them from consuming it one way or another. If it's not a violent video game, it will probably be some sort of media, tv, internet, etc.
Should some people not play violent video games? Absolutely, some people are ape shit and will be ape shit whether or not they lay hands on a video game. Should some parents keep their obsessive little shit children away from the adult world? Certainly. Blanketing rules need to be avoided. Making something forbidden only makes it more alluring, especially to those crafty little bastards.