Really, it works totally fine for Autochthon, and he has Six of them apart from Creation's five. You have to remember that Primordials are still Extremely encompassing beings, so this means that everything "elemental" simply gets rolled under its nearest equivalent and the adjustment of themes around that reclassification is what helps worldbuild just that bit more.
For example, harkening back to Autochthonia again, Lightning is its own element distinct from Air, but Fire is now encompassed by it. Elemental Lightning revolves around power, motivating drive, authority, divine might, illumination, and noble endeavors, compared to the elemental correspondences of Fire as passion, heat, consumption, quickness, and purification. What does this tell us about Autochthonia, and its metaphysical priorities? That it is less "human" and more divine and high-minded, that it is more cold, sterile and unfeeling in its approach to aggression and conflict. Fire burns, lightning kills. Its the little things like that which help build up "what this setting is About" when you have a game like Exalted and so much is contingent on using and interacting with magic.
Now, assuming that "Light" was a capital-e Element, with "Fire" similarly rolled under it, what would be the correspondence in a world also characterized by Dark? Warmth, hope, truth, illumination, wisdom and inspiration? What does that say about a world without these things, that Light as a concept is needed to be so centralized this way apart from sources of light, to simply Be Light?
That's the cool questions to start asking when you're trying to make something Distinct from Creation, but not Part of it.