I imagine with a mouse and keyboard, this isnt a big problem. So really this is a console only issue. Well you see, on consoles the bow and arrow controls was pretty clunky, and when you zoomed in it was even worse, you were unable to make minor movements, if you moved the stick too far it would make a small "jump" in that direction.
Also, since this is a console controller, a bit of aim assist is necessary for aiming, though it should be unnoticeable.
For melee combat, i dont think any aim assist is necessary.