Who will grow up to routinely do calculus mentally or on pencil and paper? I guess some people will be calculus instructors. Are there any other examples?
I mean, if you're an engineer and you don't know the relationship between position, velocity and acceleration - you're going to have a bad time.
(I am one)
I have no idea. So I will gladly defer to those who do understand math, and be glad someone does, or my career wouldn't exist.