The bit that so many of you are missing, which is a really salient point, and you are so quick to flobble your jowls about the fecklessness of youth that you are missing it, is this:
What the teacher did was not to demonstrate in a hard-hitting way that a certain humiliation was possible, as some of you think. What the teacher did was to perform the humiliation.
So - you jowl-flobblers - your argument is crap. You are like a person breaking someone's leg to show that legs are breakable, and then sneering "it had to be done, they are lucky it was done by me with love rather than by a stranger". which is illogical crap.
Obviously what makes this attitude actually nasty is the lack of empathy and compassion, rather than the lack of logic, but I find that people like you are with misplaced senses of superiority are more discombobulated by exposure of failures of cognition than compassion, so that is what I'm picking on