The point isn’t to have an intuitive sense of what a millimeter is just by knowing what a meter is. You have to learn both units individually to have intuition about them. The point is to know that a measurement of 500mm is 0.5m without having to do any math in your head beyond moving a decimal point.
Yes but when you don’t have that intuitive sense through extensive use or being born to it, the math gets in the way as you’re trying to form it.
I’m an American in my mid-forties and that has not been my experience at all.