I don't know, exactly. I would hypothesize that that the benefit comes from shortening the lever arm between the ankle and the pedal, but that's just a hypothesis.

I'm generally a "ball over spindle" pedaler. It doesn't usually take long for the nubs (they'd be "spikes" on higher end pedals) on my BMX pedals to wear corresponding pits into my shoes. On tour, after a few days worth of climbing steep hills, instead of pits, I had grooves, because I had moved my foot fore and aft on the pedal to maintain maximum pedaling ease. I'm certainly not the first person to notice this phenomenon.