Children have boundaries for their own safety as well as to prevent harm to others. Adults aren't really that different. Boundaries for behavior are useful when living within a society. There isn't anything magical about being an adult.

Of all tyrannies, a tyranny sincerely exercised for the good of its victims may be the most oppressive. It would be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated; but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience.