[naasking]

> Well, yes, it's a model for the physical world. Refusing to accept that the state vector is the real world we inhabit is tantamount to rejecting the existence of an objective universe, in which case any discussion is moot

Some physicists consider the wave function to be ontologically inadequate to explain the physical world. See the discussion of "bohmian mechanics being many worlds in denial" for some details and references:

https://plato.stanford.edu/entries/qm-bohm/#ObjeResp

[myridium]

It may be inadequate, but the consequences of quantum theory still apply without having to add new postulates. Among those consequences is many worlds.

[naasking]

Saying it's ontologically inadequate means that it's insufficient to describe what we consider "real", and thus the wave function by itself cannot describe one world let alone many worlds.