It's called getting along and exhibiting good social manners. Hello.......?
It's sort of why guys sign up to play sports.
You hope someone will say,
"Hey, that was a good play!"
It's even kind of fun to say those things to the other team.
A happy opponent doesn't try to kill you either.
When playing football, I always like to find something nice to say to the other team. It hurts less that way.