i think the point of this argument, which i agree with, is that they wouldn't run full speed into each other if they didn't have the helmets. you'd see more arm tackles. i agree that it would probably reduce injury. the argument is the same with the minimalist running movement: with less padding under your feet when running, you're more careful how and where you land, and how hard. so less pounding, less joint damage. the same would probably be true with football, i guess. without helmets and shoulder pads, tacklers wouldn't make missiles out of their bodies. there would still be concussions, though, from incidental contact. but i bet if they just removed the facemask, you'd see concussions almost elimitated. you'd still have the helmet protecting the skull from contact, but the absence of the facemask would keep people from flying into people with abandon. it will never happen, of course, but i agree with the OP in theory.