quantum mechanics - Is the wavefunction a real physical wave or only a mathematical abstraction?

Does interaction with physical slits in a double slit experiment indicate that the wavefunction is a real physical wave, as opposed to a mathematical abstraction? This question pertains to the psi ontology debate as described here https://arxiv.org/pdf/1409.1570.pdf. In summary, the debate is about whether the wavefunction is a real physical wave as the psi-ontologists claim, or simply a mathematical abstraction that provides information in the form of probabilities as the epistemologists claim. Why doesn't interaction with physical slits prove the wavefunction is a real physical wave, i.e., an ontic entity?