If you mean that minimizing the amount of time spent in backside mechanics is the key, then I would agree. I think this is what the last sentence of your post is meaning. Including one word in the first sentence, “the idea that reducing backside mechanics are the keys to speed seem to be popular nowadays”, then I would definitely agree.
There are only two situations in the sport of track and field that I can think of that purposely spending a greater amount of time with the foot and leg in backside mechanics is beneficial…and that is immediately after take-offs in the triple jump hop phase, the pole vault take-off…actually probably the javelin throw as well. Those are big acyclical movements (at the end of run-ups) that mean to put a large amount of stretch on the hip flexor, and in the pole vault (and javelin) on the abs and shoulder as well. In a continuously cyclical movement such as sprinting backside is bad.
Charlie himself uses the analogy of the bicycle crank. The faster you want to be on the front side of the crank (which is the goal), the less time the other foot can dangle and spend time coming up the backside of the crank. He uses the bike wheel and crank for a lot of good analogies to sprinting and accelerating.