I don't know much about rugby (of either or any kind) but I'm under the impression that it has some kind of a culture of mutual respect. That might mean the pla

I don't know much about rugby (of either or any kind) but I'm under the impression that it has some kind of a culture of mutual respect. That might mean the players tend to exercise greater and more conscious control in taking contact despite the sport being rough. I'm also wondering if that's partially connected to exactly the fact that they don't wear protective equipment. In many cases it's of course definitely helpful to have protection, but since it can also make the risks less obvious, using heavy padding might also encourage heavier contact. If, on the other hand, none of the participants are under any illusion of safety, that could discourage recklessness and perhaps even encourage a sense of mutual respect. Helmets generally don't offer that much protection from concussions. They do reduce the risks of other serious head injuries such as fractures, as well as more superficial injuries, but if helmets make people think they can take heavy contact with abandon, that might increase the number and severity of concussions.