If the smallest input you can manage on the rudder creates far too much in-game response (i.e. you add a minor amount of rudder pedal and shoot way past the actual target, let go, jump back to the other side) you scale the input, so that it takes the same rudder movement (how much you apply) and reduces its actual impact in-game.
End result is you get finer control, you have to move the input MORE to get more input, but in those finer moments when you need it, you get exactly what you want.
It also helps slow down E-bleed from major rudder movements.
