It probably depends on body type/shape. I'm not fat, but have a broad barrel chest. My elbow rests on the surface my back is on and my forearm length is perfect to put the phone at the right distance, while my forearms rest against my rob cage.

My physical disability is from thoracic spinal damage. Basically posture, and the muscles it takes to lift arms like pictured. Holding a phone like this is often the only thing I've been able to do physically for the last 10 years, because of both strength and how I flop around. I think maybe you just need a little more technique, but I'm probably body-type biased to myself ;)