In The Giver, why do people have to report their dreams and share their feelings in Jona's world?

Jonah's world is based on everything being safe and the same.  All of the memories and emotions are only carried by The Giver.  People have to report their dreams and share their feelings to make sure no one has any negative dreams or feelings and to stop them early if they do.  So when Jonah reports the dreams that signify his "stirrings" they can give him medicine right away to take away the stirrings and the emotions they cause.