That wouldn't work for multiplayer. Plus it's already fairly easy to read the field as a QB simply because of the view we play the game in, no real need to make it even easier. The original vision cone was really a great way to do it, but people didn't want to change, and whined about the flashlight effect.
A better option might be to limit the number of visible receiver icons for lesser skilled QBs. Manning would see all 5, JaWalrus Russell would only get one, maybe. The other receiver buttons would still work, but you'd only see them in the pre-play coach view.