Because we can create our own framework. And also because we can optimize it to our solution. We don't need pssm shadows, ... But we need a simple solution for a flashlight, lightflares and many customizable lighting stuff in the video you can see some nice lightshafts through the door they are just some simple sprite model with one of our shaders attached (it's the same shader for the lightflares at the lights). the modification to use it for lightshafts took me about 2 minutes so i know my framework and know where to change stuff to get cool effects
