Which is what an ARB does. For about $50. And for that price, I like the fact that it's all one unit, I don't have to worry about contamination getting into the valve stem, or dropping a core; I bet you a dollar it's not appreciably slower than pulling the core alone either, since the openings on the ARB body are bigger than the valve stem. Those who mention gauge consistency over calibrated accuracy are right, but maybe it's just the professional mechanic in me; I like both. My air gauges that I use regularly are all ANSI certified accurate because accuracy matters to me.
To each their own, after all; but for the amount of money people spend on stuff they might use once in a blue moon, I think $50 is a pretty cheap pill to swallow for something you'll use on every trip. Regardless of whether you go with screw on deflators, or ARB, or another type.