Whatever it is called that causes the following scenario in any shooter:
You're aiming at the high-priority target who's maintaining distance from most of the fighting and either supporting his side or ruining your side's day, or getting ready to. Much hinges on your taking him down in the next couple seconds. Suddenly you have an opportunity, you line up the shot, it's perfect...
... and just before you pull the trigger, a low-level minion runs through your line of sight, and the game engine causes your crosshair to track with the minion rather than your target, you fire, and miss both because the engine is only willing to move your crosshair, not make it accurate. Bonus points if that missed shot was all the ammo you had for that weapon. Further bonus points if you die or you fail the objective because of this.
There's never an option to turn this feature off, even though in the ten years that this feature has polluted every single shooter out there, it has always displayed this behavior and has never been welcome.
I have spent a lot of time imagining the things I would like to do to the person who thought this was a good idea. Certainly, I think it's important for the future of the industry that he is at least found out and blacklisted or otherwise prevented from working in the industry ever again, so that he doesn't do any further damage to otherwise good games.
I suspect he's the same guy who designed the notoriety system for Assassin's Creed II, specifically the wanted posters in alcoves on roofs and the curious fact that certain stealth moves raise your notoriety. I suspect he's also responsible for the mineral scanning in Mass Effect 2, and many other embarrassments to the medium.