The why do they say let insted of net if the ball hits the net why not say net?

Question

The why do they say let insted of net if the ball hits the net why not say net?

Answer 1

well if they say net it sounds like et so they say let cuz it sounds like net so to our ears it sounds correct

Answer 2

The reason is that let not only means to allow but also an impediment or hindrance, exactly what hitting the net on the serve is.