Teddy Roosevelt loved the sport because he thought it was a good way to instill young men with imperialist values and keep them hyped for war during peace time. It was also a lot more deregulated back then. Helmets were leather and weren't mandatory, there were no face masks, tackling was a lot rougher, dogpiles were the rule rather than the exception, long distance passing almost never happened and every play was about ramming through the defensive line with full force, and deaths were a regular occurrence. They also played on real grass with sticks and rocks coming up out of the ground instead of on astroturf.