Chainsaw Repair

I have never messed with stuffers before, but I have seen them before when working on a Husky cut off saw.
   I am curious as to what the advantage is.   I realize that your reducing the volume in the crankcase and in theory this gives more pressure in the crankcase when the piston is traveling down.   
But does it not also reduce how much air fuel mixture that will enter the crankcase when the piston is traveling up. 
If so it sounds like a trade off to me.