It's been proven? By whom? Hollywood producers and directors? Scientists whose funding is predicated on a pre-determined outcome? Give me a break. Football has become too big and financially lucrative for the "powers that be" not to get their hands on it or cut it down to size, so to speak.
Football is a violent sport. It's been a violent sport for a long time. It was a lot more violent in the 50's, 60's, 70's, 80's, and early 90's. Where are the endless line of players suffering from the effects of having played football? Are there some? Yes! Are there enough to demand this assault on the sport? No!
More people started watching with the increase in popularity and a small, powerful segment of the audience saw the sport as barbaric and decided to do something about it. They have and will continue to do so until the diehard fans barely even recognize the sport.