Remember that fish have a conical range of vision. Their eyes aren't pointed forward like human eyes. They have far better peripheral vision than we give them credit for. So when there's not trees for you to blend in with, you're going to stick out, and they're going to eventually see you. Even if you're being still. Sure you can stand 80 feet behind them and fire your casts from there, but what good is an off-target long bomb when you can make a shorter, accurate cast? All you have to do is simply drop your profile.