The people that I have disagreed with the most have usually turned into my best friends. Which is kind of funny. Since it shows a person can stand up for themselves. As you say it makes people consider their world view and behaviour. Makes you grow.

Yes people get hurt for a day or two. Then they learn more and consider their behaviour in life and learn more about themselves. Most stuff in life is just misunderstandings here and there. Also makes people respect each other much more in the long run when you have been through more together.