I'm not sure what the NFL does that's wrong. Their players get significant fame, are consenting adults, and get pay checks that many would trade even more of their health for. It is the college level, and especially the high school level, that I see the major problems at. When you have kids, or even people who aren't paid, risking their health it crosses a significant line. If college players were paid, and if playing below 18 (or even 16) was banned, it wouldn't be a big problem for me.
Edit: As someone else pointed out, the suppressing information is wrong. I wasn't considering that side of things.