Whenever we talk about protection, I always harken back to the study that said kids who learnt martial arts with body armor actually ended up getting hurt more

Whenever we talk about protection, I always harken back to the study that said kids who learnt martial arts with body armor actually ended up getting hurt more than the kids who don't use em. We see a similar effect in case of body immunity etc: Third world countries just live through so many environmental effects that they build a natural immunity. IOW, I wonder if it is sane to restrict these or just let people figure it out: I remember a time when everything on facebook was about zynga games and then they just went away. I mean the ability to focus on a given task persistently has produced so many good results: Why wouldn't we want to hone and develop that by providing as many distractions as possible?