Jerry Rice has admitted to using stickum on his gloves for the duration of his career, (which began in '85) despite it being illegal since 1981.
Aaron Rodgers has admitted to overinflating footballs to gain an advantage.
Multiple players have been penalized over the years for using non stick cooking spray on their jerseys, despite it being illegal.
Most of all--EVERY SINGLE NFL TEAM has at least a handful of active players guilty of Performance Enhancing Drug violations. In fact the SEATTLE SEAHAWKS LEAD THE LEAGUE in the number of PED violations since 2010 (ie. under Pete Carroll). You're telling me that fact alone isn't connected to their dominance?
The point being--EVERY team and EVERY player tries to gain a competitive edge--mostly they just push the boundaries of the rules, usually breaking them.
Maybe Brady should be penalized (he probably should, even though the report is pretty hazy about what actually happened), but this in no way should tarnish his legacy.