Hmmm, interesting topic. I did my initial twin training in Bisbane, Oz. My instructor frequently pulled the mixture back to create failures, including one on take off (fully brifed though) and one on downwind for our final landing when I feathered the right engine on the Duchess for real. Great fun and experience. My instructor was highly experienced ex DC3 pilot who had being flying around Northern Territory since I was a tot.
I never realised it was other than common practice elsewhere.
I assume that one advantage was that when he pulled a mixture back, he could easily cover it from my sight with a clipboard so I was forced to work out the dead engine without cheating. As soon as I had done the 'all the levers forward' movement, he would set zero thrust on the dead engine, and then I carried on.