As for the harassment during training such has been described here, to my knowledge that has never been a standard part of any agency training. A history of NAUI written by Al Tillman, NAUI instructor #1, describes the first true training session in Houston in 1960 during which they were surprised to see instructors doing this. His conclusion suggests that he believed that the people doing the harassment were more motivated by the fun they were having doing it than by a belief it was helping students.
My profession is educational theory, and I find these activities dubious at best in their educational value. I won't go into the details of why I don't see the value, but suffice it to say that whatever value it may have is overshadowed by the danger. Let's say you rip a student's mask off at 10 feet of depth in the pool and discover that, by golly, he did indeed panic and sprint to the surface while holding his breath. So, will you feel a great sense of satisfaction in your role as an instructor as you remove his corpse from the pool?
You may not have seen it directly in the standards, but there are agencies that have minimum standards (such as CMAS).
And I wouldn't call this harassment. Swimming along and get a mask pulled off is just something that will eventually happen while diving. It's not like the instructors are attacking a student. Isn't the purpose of training to teach and prepare the divers to deal with situations that may happen during a dive? There is a lot of teaching on sharing gas, controlled emergency ascent... things which derive from being OOG. Well, I have never been out of gas and have had my mask and reg kicked or pulled several times.
Is it better to remove all danger from a class, where the exercise is done at shallow depth and with an instructor right there prepared to intervene and then have that situation happen to the certified diver at 20m without anyone being able to help? Maybe in American instructor's eyes it's better since it didn't happen with them, they can't be sued. Still, injured or dead diver due to lack of training.
And of course these exercises don't come out of the blue and are not done in a 3-day course.