I still don't get it :) ...

In 1v1 the GF is not time/distance dependant, because if they had time to move another tick perpendicularly, then the bullet had time to move another tick towards them, keeping the angle constant. It's not exactly the same with DV, because you are not storing the angle but rather a velocity which needs to be scaled by the bullet flight time, but in essence I think the concept comes out pretty much the same.