Most liqour brands do this, I think mainly to meet whatever the local and state regs are for alcohol content sales. Like here in ohio, you can only buy liqour over 80 proof at "state" liqour stores. Everyone that sells liqour has to have a state licence but certain state approved liquor stores can sell the higher proof stuff. So you can get a bottle of just about anything that's 80 proof at the grocery, gas station, and drive thru package stores.
I suppose it seems like a big deal but its how you cut moonshine when distilling it so it doesn't seem that outrageous to me.