Why must The Edge Vent be installed on a minimum 3/12 roof pitch?

At 3/12 and steeper roof pitch The Edge Vent is graded downward which helps prevent water pooling.

At less than a 3/12 roof pitch there is a point on The Edge Vent that is no longer graded downward. If The Edge Vent were installed like this there would be the possibility for water pooling which is not desirable.