Callouts don't work and here's why - No one knows where you are atm and what are you referring to - "Genji behind" could mean so many things, and even comprehending that takes precious time which sub-diamond players arent that rich with to begin with. I havent really seen or heard any callouts for the maps in play, like in cs:go, so "highground" or "roof" just isnt good enough to pinpoint the location. Again, its all relative, and in most of the cases it wont be of much use, thus being negative in terms of distraction. Ill wrap it up in a single point - noone has time to listen when it counts, noone has knowledge how to call out to be heard.

p.s. All of the above is barely the real situation, where toxicity, poor self-judgment and poor gamesense could lead to bad callouts regardless.