I was a light green Marine in Vietnam from 68-70 and I remember it a bit differently. The dark green Marines started the custom and it was often called "giving power" but I don't remember there being any hate aimed at it from light green Marines. Indeed, many light green Marines embraced the practice as a matter of brotherhood although it remained primarily a dark green thing. I don't remember it being banned anywhere but then I wasn't everywhere.
Where did you get those stories? Your personal experience? I understand that we had many different experiences in Vietnam but I didn't see it quite like you describe it. Certainly not a norm.