Some people prefer the feel and connection of a controller, a device made and developed over decades for the exclusive purpose for controlling a video game, as opposed to the mouse and keyboard, devices made to replace the typewriter that gamers and developers adapted to. Why is it that PC fanboys can't leave their entitled arrogance on the back burner for one moment and answer that question themselves because it's actually very simple. Personal preference.
Yes, M/K is more accurate, but by that logic people shouldn't be using touch screen to aim and fire a gun in an FPS? Just just touch the screen whare the player your shooting is at and there you go, but it's kind of a detach from reality. That's why I never play and competitive FPS on PC and never will. With a user interface that's all about winning, that makes the game all about winning, and nothing else. Yes, dual analogue is less accurate, but it's also closer to the reel feel of using a weapon, making the experience more immersive and enjoyable for me. So, go ahead and revel in fact you can point and click faster than I can actually AIM something, because I don't care. I'm not saying that a gamepad truly reflects how a real assault rifle feels either, but with triggers and vibration it's at least closer than rested hands pressing keys on a keyboard and clicking a mouse.
If the only reason you're playing a multiplayer game, if the only joy it offers, is through winning, then consider the possibility that maybe it's not a very good game.