Yeah but as far as I know they are locked near top or bottom of the phone and in addition they are really close to the hand (in my case the hand I handle the phone), which makes it hard to reach them as well, even not talking about extra movements you add.
So it would hard to reach thsoe shortcuts as well. Also it would ruin the flow of the phone usage, where I would need to scroll all the way back to the point I was previously (for example some reading in browser) or is there shortcut to get back from top/bottom to the point you stopped reading before making mega aka mortal kombat fatalities combos to get to the one hand friendly pulley menu?