Imagine working in an environment where you are terrified to talk to your supervisor. As soon as he says the words, "Mr. Y, I'd like to see you in my office", your stomach starts churning and you have an uncontrollable urge to start feeling your morning breakfast coming up in your mouth.
From experience you know these meetings are never pleasant. He only holds the meetings to berate you and tell you how awful you are and how he can't wait until you leave. Most of the time almost everything he says is unintelligible and impossible to understand.
In school I was taught that the supervisor is there to help me become a better teacher and to help me deal with situations I could not deal with on my own. Imagine having a supervisor like the one described above. Who in their right mind would go to a person like this for guidance? No one could become more proficient in a job with Atilla the Hun in charge. Even if he had something to offer, how could anyone learn a thing while they are trying to keep their guts from exploding all over the place.