1. Define high capacity.
2. Why would anybody need any gun or magazine?
HCM is defined differently depending on where you are.
I can list multiple reasons, but all are arguable. You don't "need" a car, but many would say they do. It's all relative to the individual and their opinion. I own a gun, but respect those who wouldn't. I feel no reason to push people to get a gun. My beliefs are mine and others are their own.