I have - on more than one occasion - seen people who needed an extender in exit rows (British Airways for example). On one occasion one poor guy was squeezed between two VERY large men (for a albeit short flight - 1.5 hours).
I can't imagine what he thought after the thrill of getting an exit row seat and then discovering that there would be almost no space left for him between the two other guys. Unfortunately the plane was full to the last seat.