Because of a power grab by the Executive Branch, or something like that.
In 1905, 18 men died from football-related injuries. At the time the sport was largely a collegiate past time. Despite the academic setting play was brutal, with gang tackles and the random haymaker. After the rash of footballer deaths, President Theodore Roosevelt summoned representatives from Yale, Harvard and Princeton to the White House.
The meeting led to the formation of the American Football Rules Committee. Aside from banning all gang tackling, the committee introduced the forward pass and doubled the yardage required for first downs from five to ten.
Teddy’s soft spot for football might go back to his adventuring days. Ten members of the Rough Riders, the military regiment that fought with Roosevelt in Cuba, said they played football professionally when they enlisted, according to the Theodore Roosevelt Association.