This seems to me as backward reasoning. Maxwell’s equations were descriptive of an observational phenomena, which was electromagnetic oscillation, and Schroedin

This seems to me as backward reasoning. Maxwell’s equations were descriptive of an observational phenomena, which was electromagnetic oscillation, and Schroedinger’s equations used amplitudes to unify them as an energy conservation law. The author asks “why not quaternions”, and gives the reasons, for which he concludes that complex numbers must be the only fabric of the universe. This is backward reasoning, and also narrow to the author’s specialty. Quaternions are just one of many choices for a 4th-degree extension field of the reals, where complex are the only choice of 2nd degree extension. Yang-Mills theory uses Lie algebras of higher degree to form an energy conservation law that unifies the observations of electromagnetism with other observations made at high energy, of which the complex numbers of electromagnetism are a subset. The article appears to suggest that QM phenomena exist because of the mathematical curiosities of the complex numbers applied to linear operators. Its not my place to say whether the universe “is” mathematics, but I do feel comfortable using math as an attempt to describe it, and there may be many choices, but our convention generally is to choose the description that eliminates possibilities that are rejected experimentally, and many such may be required, but our secondary preference is to choose the smallest set of descriptions that contain the observations.