You just don't want to respond - and I speculate that it's because the answer would completely invalidate your position.
In my experience, when someone says "that doesn't merit a response," it's because they can't be bothered -- or don't know how -- to think of a rational argument. They'd rather just throw it all back on you, i.e., the ad hominem response -- the lazy irrational way to argue.
Andria

