I'm having some trouble understanding the usefulness of the operator notation we just covered here. I decided to come back to this after doing Project 3-1 since I figured we might see it being applied there. However, since in practice we're doing Monte Carlo integration, it makes sense to simply sample incoming light directions, find their intersection points, then recursively compute the radiances at various surfaces along the path. Even when talking about the rendering equation conceptually, this notation doesn't seem particularly intuitive or easier to write than the earlier one. Is there a scenario in which we'd want to make use of this notation (either in code or theory)?

Just for reference, this (I - K) portion actually corresponds to the fact that I * L = L, hence what we have here is L - K(L) = L_e, which confounded me at the very beginning