this does not in any way address the issue of having not enough or too much of a substance being formed by atomic reactions
Well yes it does, sort of. What formed under linear spatial and planar temporal may not manifest the same way something formed under the volume of temporal and volumetric of spatial ... for example. The photon crosses the Universe always in the present of the moment of its creation, relative to the source from which it arises. The photon is a little pinch of time (a moment as it were) and a point of space, traveling the Universe in a linear trajectory. To the photon the Universe is linear. To the receiver of the data of the photon the Universe is planar or volumetric.