There are some kinds of cheating that they can detect and a whole lot more that they can't. With the latest cheats you can literally get an online AI to aim for you. And it isn't code you patch into your copy of the game. It's just a separate computer playing for the player instead of them playing for themselves. The best analogy I can think of is if a normal player handed his controller to a friend to play for him. There just isn't any way for any developer to police that, to know whether or not a player is legitimate or a bot. I'm not trying to go easy on Respawn. They have a lot to answer for. But in this case, for once, I really don't think there's much they can do.