During my service in the Army, I have often come across senior officers boasting, “I tore that fellow apart. He will remember it for his life!” There are also a number of retired generals who have had the reputation of being abusive. At the same time, I also fondly remember seniors who were understanding, courteous, and helpful. They would listen to their subordinates. When the juniors committed mistakes, they would correct them and move on.
In a position of authority, it is easy to humiliate subordinates, mostly because they don’t retaliate for the fear of losing their jobs or earning a black mark that would affect their career.
The insult certainly does not boost output, but it leaves a scar on the person, demoralising them and marking them negative and remorseful.