Overwatch has made the decision that closest cheaters are not a problem and have actually protected a cheater in contenders, although they were forced to leave the competitive scene. None of it ever became public.
Word of mouth, but if you looked at their twitter and proof presented it was undeniable. If you want to go digging check a french contenders player that there are videos of with an instance of where the aimbot bugged out and started aiming directly at the center of a player with perfect reaction time and movements.
