This is just an opinion as I have no more evidence than anybody else about the unexplained breakups in cruise flight. However 20 plus years of teaching and examining in R22's suggests to me the following. If there is an unexpected power loss, the first reaction is "what's happening"? Followed by either far too slow lowering of the lever or no reaction at all. Result- massive drop in rpm, rotor blow back and break up. I have had two examples of this lack of reaction to real engine failures but not in R22's and in each case I had to slam the lever down. Sadly Robinsons edicts about simulations of engine failures result in most people have no experience of the rapid rundown in rpm in the event of power loss (and it doesn't have to be a total loss). Again my observation of people's behaviour suggests that the most likely cause of the power loss is due to lax operation of carb heating and undue reliance on the carb heat assist. Whatever the reason, if you get an unexplained power loss in an R22, after the inevitable " this can't be happening to me", you have to slam the lever on the bottom as fast as you can move your hand. Even then, the rpm will go down into the 80's. Unfortunately the autorotation entry as normally taught is much slower than this scenario and unexpected complete shutting of the throttle discouraged.