Our OWD class included some drills like that. The toughest one was called "blackout doff and don with harassment". You were blindfolded (still had the mask on though) and took off all your gear. As you started to put it all back on, the instructors started to "harass" you... loosen straps, drag you around, toss you over, turn off your air. Completion was optional as this was basic OWD, but it was on the course program nonetheless.
Stress training such as has been described can have great instructional benefit when the student responds correctly, but one must be careful with it.
A friend who was part of an instructor training program for a technical diving agency described a situation he observed in that program. The instructor in training swam over the top of him (the simulated student) from behind, pulled the student's mask off as he passed by, swam ahead, and turned around. By the time he was around, the student was nowhere to be seen, because the Instructor Trainer had signaled him to simulate a panicked ascent. According to DAN research, panicked ascents are by far the number one non-health related cause of scuba fatalities.
In my tech training in doubles, our instructor shut off my buddy's air. He signaled, I gave him my long hose primary, and I picked up my bungeed alternate. No air. I realized that my instructor had simulated a left post roll off by shutting off my left post before putting my buddy out of air. I reached back, grabbed the valve handle, and turned it back on. At no time before that had we ever been taught about left post rolloffs or what to do with them--I just figured it out. I later heard that in another session with other students, the student in that situation did not figure it out and panicked. Apparently things got a bit ugly (I don't know the details), but fortunately no one was hurt.
If you are an instructor who includes harassment in your training, you had better make sure you are in a position to deal effectively with a student who does not respond appropriately. If you do not and have a student fatality as a result, you will have to convince a jury that your training procedures were safe and acceptable parts of diver training. If your opposition points to the fact that your training agency does not condone those practices, you will have a tough time. Even if your agency condones it, you may have some trouble. For example, the agency in the first episode I described allows the instructor to take the mask off a student without warning. Other technical diving agencies forbid that because it is considered too dangerous, and you can bet that fact will be brought up in your trial. If the student with the left post rolloff had been hurt, the fact that there had been no prior instruction for that would have been very important in the trial.