I just see this as the nature of competition itself, especially in sports - since the purpose of
competition is to defeat your opponents and become the champion.
That is, in itself, an issue. Competition is necessary for survival in the wild, building it into culture is done because of how much it props up the ideas of statism, nationalism, corporatism, and all of these other sociopathic issues we are dealing with as a species. Conditioning is always going to have much wider-reaching ripples than the immediate physical activity that's being looked at.
Even if it did, there's nothing coercive or harmful about liking your favorite team or disliking another team.
Except for the fights, riots, and other violence that often happen around large sporting events.