And if someone can explain well what a piece of code is doing, then of course that person can also write code. I can read and understand many mathematical proo

And if someone can explain well what a piece of code is doing, then of course that person can also write code. I can read and understand many mathematical proofs and explain why it's true, but I could never have proven it myself. I can read and understand most of the great novels ever written, and even try to explain their greatness, but I could never have written any of them. That being said, I agree that listening to someone explain and critique written code probably gives at least as good insight into their coding ability as having them whiteboard a leetcode problem.