Comment by cosmophany

1. In practice, experimental physicists can and do disagree all the time about what their apparatuses are doing, what the results mean, and so on -- at least, they do at the beginning of the experiment. By the end, they have gone through a process that results in agreement, which allows them to write a paper together declaring things in an objective manner. So it is important to distinguish between the "inputs" to scientific practice (our individual, subjective initial guesses about what is going on) from the products of that practice (effectively objective statements). QBism interprets wavefunctions not as products but as inputs: we need to start with a prior "best guess" about the probabilities, and it its the interactive process of updating our subjective priors in light of data that leads us to converge on a single wavefunction, which then attains an objective status in the sense of being the same for everyone. QBism's point is that this whole process of "objectification" is itself a process to be analyzed, not taken for granted as if the objectivity were there from the beginning.

2. The PBR theorem (which you cite) doesn't bite QBism, and PBR themselves admit as much in their paper. See point 8 in [https://arxiv.org/abs/1810.13401].

3. What you say would be silly, if QBism treated classical states as "more real" than quantum states. But they don't.

QBism treats quantum and classical states on the same footing: both are sets of subjective probabilities about the outcomes of possible measurements you could do. So classical states are probability distributions, and probabilities in QBism always represent subjective degrees of belief of an agent (following the de Finetti/ Ramsey school of probability theory). The difference between classical and quantum states in QBism does not lie in what the states ARE, it lies in the rules that tell you how to compute one state given your subjective beliefs about another state. And those rules are objective in QBism; as objective as the rule that says probabilities have to add up to one.

4. Doubly ironically then, this is probably the one point raised by critics that hits the QBists hardest. QBism can bring clarity to many issues (I find it handily resolves the measurement problem and non-locality of "collapse" - see eg.[https://arxiv.org/abs/1311.5253]) but there are still plenty of physical phenomena that don't yet have a neat QBist explanation.