Punishments that involve physical harm, or fear of physical harm, are clearly immoral and unethical. I include spanking in here, and also p4's sauna story. To me it is immaterial that no pain actually occurred. You shouldnt be teaching children a "do this, or fear injury" way of living.

Yes, it is important that children understand that their actions have consequences. It is also important that they understand how to behave properly. But nowhere in parenting should punishments involve what would normally be considered assault elsewhere.

(Yes this is very general, and im also sure P4 is an excellent parent and that im misinterpreting something in his story. But the point is still that people, even children, should feel safe)