Letting people make mistakes teach people a lot in exploring better ways. Doing the reverse action will cause people to make effort on hiding the mistakes rather than trying to become better.
The most obvious case I have seen in enterprises is the role of managers: Managers usually pushes people not to make mistakes by using their power, the source of which is the processes, plans and policies behind. That causes a lack of feedback because making mistake is known as something “all wrong” although it may contain lessons in it. That’s why people hide problems or try to put themselves in a position that they never make mistakes.
Furthermore they intent to show themselves as “perfect”(Describe perfect as accomplishing a task as written in the process or plan.). If an individual defines her/himself as ‘perfect’, that individual will not try to become better, since that’s the end point. The feeling of perfection would lead Kaizen culture to be lost or never dissolve. Enterprises and individuals better embrace and tolerate self mistakes and let people find solutions by their own. That would make better decisions to occur and improve the goal achievement.