aircon66

Apologies, my previous post was wrong. It seems that you can alter the mix on the middle selector. As you roll off the neck volume pot it progressively reduces the neck pickup output but retains the bridge pickup output until you get down to around “1” or below, at which point it kills everything. The bridge volume pot acts similarly by cutting the bridge output and keeping the neck output.

You cannot "zero out" the volume of one pickup on the middle selector. That is the OP's original point. Yes, obviously you could select neck or bridge if you only want to use one pickup, but the fact remains that on the middle position you cannot "mix" individual pickup volumes.