I guess my thoughts are, why would you? The only time you would use VFX is if you can't do something in real life cheaper, and since it's extremely expensive that rules out filing the frame with mundane realistic objects.
Aside from time and budget, art direction and production design often rules out a photorealistic look anyway, even if technology allows it.
I'd like to dig further into what you mean by photorealistic CG being fiction? There are still tricky areas that are actively being researched, but I've seen plenty of CG assets that are photorealistic.
What do you think is technically missing from CG video, that makes it lack realism?