Vision Score

Hey, I play Teemo pretty often and was wondering, why do shrooms not count for vision score? They are an ability like the ashe arrow that provide vision and information and often damage. I use mushrooms more often than i use wards to keep vision and protect myself and late game I use them super often to catch vision of enemies in their jungle and do damage. Even if the score they provided was 1/4 of what you get from other sources, it would be helpful to the vision score for showing reality. I know it may seem like an op thing for someone like Teemo to have but the vision score just represents the reality of vision time in game and the shrooms are a major part of that in any teemo game.