t'aint natural,
Not sure about your analysis of the problem, in the sense that I see both ends of the EOL as important.
There is more than one interpretation of the accident history you quote (assuming it is true). It could be that it ain't possible to get the lever down fast enough in a Robbo in some circumstances - but that would go back over old ground that I am not overkeen to revisit.
The guys I used to be most worried about were PPL private owners who never used to practise autos at all. When you eventually persuaded them to go and do some dual time, the autos were just horrible. I often felt they would not have responded to a real engine failure at all. But aside from extreme cases like that, just how difficult is it to push a lever down promptly??
I always used to do a small number of throttle chops instructing on the R22 (both demos and for the student). Mind, if there was any student hesitation the lever went down anyway, so I am not sure exactly what it proved. I always thought it worthwhile to give some practical idea of the indications of engine failure.
In the US of A, I believe that they do shed loads of chops, but others will be able to comment on that.
My feeling is that any pilot needs to be competent and current at both ends of the EOL, if you fly a single. The level of competence ought to be considerably greater, if you are a professional pilot.