Very true. Even dance competitions for girls are good character building. It teaches winning/losing gracefully, teamwork, and just hard work period. Team sports are great for kids. No matter the type.Before a kid signs up for an organized activity, you've played sports with them or seen them play against other kids.
Can see how competitive they are, and what drives them. See how they handle winning and losing.
When they sign up for camps, teams, and leagues you can give them encouragement and support, but how they respond to competition will teach them about life.