The bow hold is the place where the whole analogy of driving a car vs working on the machine really lines up.
If the wheels are on sideways it's gonna be tough to drive straight no matter how good of a driver you are.
Similarly there are angles of the hand to the bow that make it possible and easy to bow straight.
(Aka achieve perpendicularity!)
It's not about correctness just for correctness sake. The actual goal is to discover the most relaxed effective hold for your unique hand.