Bob: "So, if the boot cuff flex is linear with heel/toe, [...] wouldn’t the force exerted on the side of the boot cuff extract more leverage?"
I really don't think so - your calf muscles make up the difference and then some.
Do a little experiment. Go outside and do a 25 yard dash and time yourself. Then do it again without letting your heels touch the ground - run like a cheetah, all on the balls of your feet. I guarantee you will be faster. There is a similar advantage to using your feet/ankles/calfs while carving. Ignoring your ankles means you're doing more work moving your hips and shoulders over the board.
But as several people have noted, there is a balance point where ankle action and body alignment are optimized, which is why we don't all carve at 0/0. This point may or may not fall with your toes/heels on the edge of the board. But starting with them there is a good idea, especially if you don't know where to begin. With Sean's and my own empirical evidence, I stand by that recommendation. Myth... harrumph!
I'm afraid my articles have given you the wrong impression that the ankles aren't part of the equation and it's all hip to hip leaning. I wrote many of them at a time when asym boards and heel-to-toe asym technique were still popular, so I emphasized the benefit of lateral hip movements, perhaps at the expense of giving the ankles thier due credit.