another thing to realize that is that hope to develop the ability to render out multiple passes, both for artistic, but as well as purely functional reasons. For example, we might want to add elements that are only possible in an offline renderer, and we would have to then blend them in a shot with minimal effort, make it occluded by elements rendered in UE, have it cast reflections etc which would then require full raytracing. the idea is that UE would be just another renderer in the pipeline, though hopefully the primary one. So at the end of the day the pipeline needs to support all that and not cause special cases that would cause two shots sitting next to each other to look quite different.