The argument depends on few assumptions. One is that a system has a “real physical state” – not necessarily completely described by quantum theory, but objective and independent of the observer. This assumption only needs to hold for systems that are isolated, and not entangled with other systems. Nonetheless, this assumption, or some part of it, would be denied by instrumentalist approaches to quantum theory, wherein the quantum state is merely a calculational tool for making predictions concerning macroscopic measurement outcomes.
Skimming the article I haven’t found a precise definition of what having a real physical state means (which would be interesting and important in such a discussion, especially given the authors scare quotes around the term). Nevertheless, the assumption that the system has a state is quite a strong one. If one wants to deny that the wave function is real (whatever it means) one can easily deny the reality of states, and treat QM only as a tool predicting which sequences of measurements can happen and how probably.
From the article:
Skimming the article I haven’t found a precise definition of what having a real physical state means (which would be interesting and important in such a discussion, especially given the authors scare quotes around the term). Nevertheless, the assumption that the system has a state is quite a strong one. If one wants to deny that the wave function is real (whatever it means) one can easily deny the reality of states, and treat QM only as a tool predicting which sequences of measurements can happen and how probably.