Purity derived through terror can hardly be called purity.
"Train a child up in the way he should go, and when he is old, he will not depart from it". "Foolishness is bound up in the heart of a child, but the rod of correction will drive it far from him". "He that spareth the rod hateth his son".
I didn't say anything about terror, you did. My children knew that it was not acceptable to do those kind of things at that age, and they knew punishment would follow. Say what you will, but the prospect of punishment for violating clear-cut rules and principles goes a long way toward preventing them from happening. The rod spoken of in the above quotes is not necessarily a literal rod, it is the authority and weight of responsibility of being a parent. Punishment takes many forms, but it is designed to be unpleasant and undesirable, which teaches the lesson the right behavior is rewarded, and wrong behavior costs something dear to the recipient.
You know something? It works. I have a son and 2 daughters that any man would be proud of, and they have all thanked me for being firm and fair with the discipline. It molded their character, and made them responsible and productive citizens. Kids don't innately know how to be that, you have to train and teach them, sometimes with words.