(Proverbs 29:22 KJV) An angry man stirreth up strife, and a furious man aboundeth in transgression.
Out of control behavior is a two edged sword. Notice that the first effect is on the group the “angry” (639) “man” (376) is involved with. Certain individuals have the ability to spread their turmoil to people around them. “Strife” (4066) is a social condition. Everyone is against his neighbor.
The second target of anger is the one who is losing it. His anger leads to “transgression” (6588). There is a such a thing as righteous anger but most anger is self-seeking and sinful. We would all be safer if we would just assume that the anger we feel is sinful rather than trying to rationalize it away.
So? Self control is good for society. It is good for the individual. It is part of the Spirit controlled life. That means we may still have a long way to go but are expected to be moving in the right direction.