Why not? More computationally intensive things are done to calculate lighting in a lot of modern games as I alluded to. Yes it would increase the load on your CPU but that’s less of a problem nowadays with higher core counts and clock speeds and it’s not like modern anticheats don’t steal some CPU cycles already. I think you underestimate the power of modern computers. I’m not trying to be condescending here but it is worth remembering that gigahertz means BILLIONS of calculations per second.
We’re only talking in theoreticals right now anyways, it is entirely possible that a game studio has tried this and it hasn’t worked, I just don’t put a lot of faith in modern game companies.