I certainly get your point. Yes, football and other sports are all stand-ins for war. Like war, sports represents the negative offset of the tribal impulse. The positive tribal impulse causes folks of like kind to want to work together for the good of the group. The negative offset of the tribal impulse is to fear and hate the “other,” those of different groups.
Through sporting events it is socially accepted, within reason, to unleash one’s negative tribal impulse in a semi ha ha way. One may speak of the enemy team without intending that there will be bloodshed. Of course some over the top fans do go all physical with opposing fans.
But, still, sports is a far better way to exercise one’s negative tribal offset than via war itself.