Infamous reversing dash frame screw

I'm not trying to be a smart *** but, why would you want to remove the dash as in why make it where you can remove it with windshield in? Other than taking my car down to bare metal for restoration I cant see where you'd have to remove the dash. The heater box drops out easier than a pickup truck(easiest heater core I've ever done) with the dash in. The radio , steering column pedals all that stuff comes out with dash in.