Share 'Draping a man's chest'

For the past 3 years I have seen more and more massage schools teach that a man's chest must remain covered. The draping is taught as being the same for men and women. Does anyone know where it comes from? I don't find it in any regulations. I have been told that Massage Envy requires this. Are they now determining how massage is taught?   I would really like to know where this comes from. Seems…