It has nothing to do with donations, unless you mean the revenue sharing between teams which goes through the NFL shell.. It has to do with the structure, and the structure is that the NFL shell retains nothing upon which to pay taxes on, and the funds are transferred to teams which do pay taxes on net earnings. Are you trying to argue that they should pay taxes on the money twice or more?
I’m trying to argue that the corporate headquarters of a corporation comprised of many different businesses is playing a shell game if it pretends it isn’t trying to make a profit. Non-profit means something in the minds of normal people, and it means those who are exempt from taxes because its purpose is some kind of social benefit, and because it is not merely a cover for a money-making operation.