I had a trainer once have me put my heels on a 6" block, w/ the balls of my feet hanging over the front (no contact on block with front half of my foot). Then he had me do squats in this position (not w/ a barbell, but by grasping an overturned dumbell between my legs). He said that this would help me utilize my hamstrings/glutes more. What you posted sounds about like what I was doing with this trainer. In theory, it would seem that this works, in that it helps isolate the hamstrings/glutes. But, is this what arnold and dave were after? I don't know. I'm only making a comparison between what I was doing with my trainer and what it sounds like you're describing. It is interesting, though.
Yea most powerlifters squat in flat shoe so to use their hams/glutes/hips/back. I do train on my speed day with work boots as this hammers my quads. See even powerlifters try for muscle balance to avoid injury. Hope this helps.