This has been in use since at least arma 2 and i was very disappointed to see it again in arma 3. It looks absolutely terrible. A soldier when viewed with any kind of zoom from a distance, is visibly sunk into the ground. This is done to "simulate" grass concealment when grass is out of draw distance range.
This is an unacceptable solution and ruins the immersion in ANY sniper mission. Even just using right click zoom with a rifle allows you to see soldiers sink into the ground.
The only proper solution is to Draw all grass in the distance when using a sniper scope or zooming. It would not impact performance because you would only be drawing a small amount of grass (that which is in the scopes field of view).