In two of the most popular sports in the world, hitting your opponent is part of the game. In football, the object of the game is literally to take down your opponent if they possess the ball, and if your teammate has the ball, your job is essentially to push around your opponent to keep them away. In hockey, hitting your opponent to take the puck away or just to rattle their confidence is also one of the objectives.
Both sports also have their incidents where players take exception if they believe their teammate was hit too hard, or the hit was a cheap shot.