Nice to see this topic being discussed in a reasonable manner for a change!
I know that turnbacks were taught in the RAF as I was given instruction myself in them whilst on a UAS flying Bulldogs. The instructors were also required to demonstrate them during their annual CFS check ride. Not all students were introduced to them; only those of reasonable ability and with more than about 50 hours I recall.
The technique was only to be used above 450' and was pre-briefed prior to take-off bearing in mind the prevailing crosswind and other factors, including whether or not it was a requirement at all.
When the engine was 'failed', you lowered the nose smartly to maintain 80 kts (Vy) and simultaneously rolled into the crosswind with 45 degrees of bank. This minimised the turn radius over the ground. You ttransferred to instruments to maintain accurate datums and pulled to just nibble the light buffet. After 90 degrees of turn you looked out and assessed the likely landing area and concentrated on a visula approach to a safe landing, carrying out immediate actions for the failure if time allowed. You would now be at about 100' and would certainly be within the airfied perimeter, if not on the runway reciprocal heading.
The plan was the rescue would be better effected on the field than sticking out of the bedroom window of 23 Acaccia avenue.
I agree that it should not be attempted without practice, training and above all a thorough brief. I can also see that it may cause more crashes than is acceptable. Bear in mind that at the time (mid 80s) the basic trainer was the JP 3 and 5 with 0-90 bang seats and good glide performance, so the idea of training for it seems quite sensible. With newer generation seats I guess the need may be less, though I'd have thought they still taught it at UAS/JEFTS level?
It's not an impossible turn though!
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Another day in paradise