It is difficult enough to learn to play a musical instrument, especially if one has aspirations of a professional career. Harassment, intimidation, and sexual abuse do not help.
To assume this method of teaching was ever the norm is historically inaccurate as well. As a student, one of my teachers was Ivan Galamian, arguably the most prominent violin pedagogue of the 20th century. And though he was indeed renowned for being intimidating, there were no threats, no yelling, no personal insults, no sexual belittling. It was solely that he demanded excellence. The message was clear and simple: If you hope to succeed musically and professionally, you will have to excel.