When you have an all-timer coach who beats his overweight G/T in a footrace to motivate him to lose weight, it provided not only that motivation, but also inspiring leadership for the entire team to work hard towards a common goal.
It also helped that OL to be blocking for the NFL GOAT RB, but it took great mental toughness to face Clyde Simmons, Reggie White, and Jerome Brown twice a year.
We knew how to coach toughness back then. With these soft practice rules, it might not be possible any more.