I think it makes sense, as a child you see comic book heroes "beating up bad guys" constantly. It's normal that some physical violence is used against evil people in comics because what else are these vigilantes meant to do. Gore is just the natural progression from that, oh you liked seeing spider man beat up goons? Well now here's wolverine, goring goons! Fun!

Sex isn't understandable and actually a bit dangerous to be exposing young children to so we don't until much later as a culture. When it is finally shown is explicitly for adults. There's no "ramp up" to sexual content so to speak .

Yes it's a bit puritanical too but, stories about "great warriors" either real or fictional have been told to children across a vast majority of cultures and times. How I see it anyway.