A teenager should never make an important decision alone. Do you agree or disagree?

In my opinion, it's completely fair for the teenagers to make the important decisions all by themselves. I think so for the three following reasons. First of all, a person has to learn by committing his or her own mistakes as it's vital for self-realization. Secondly, it's not right to guide the people and don't allow them making their own decisions. Finally, it's apparent that everything is dependent on the nature of the decision itself, although it's still better to avoid interfering into someone else's life.