Being a teacher isn't an easy job. You're supposed to be imparted knowledge and experience upon your students, but there are so many things you can't say, because there are so many people you must please (first the students, but more likely, their parents).
Some teachers don't care. They just want to read from the script and get that monthly (measly) pay-check.
Those that do care, usually find themselves stuck, unable to both conform to the system while performing their art.
The system has to change, and likely will, but not anytime soon. So until people get it right, do as Mark Twain says, and never let school interfere with your education.