Personal growth
To fully mature, one must surrender to the fact that we can't "know it all". And to claim such is a stunted regression to how we were as 18 year olds going out into the world for the first time.
We all have experiences worth sharing, we may know more about one subject than others. But to claim that it's all "figured out" is to shunt an apprentice into one's personal agenda.
A true teacher is willing to listen to their student as much as a student is willing to listen to them.