But I wonder why it gets so little attention...
Not sure what you mean by incompatible results. Certainly QBism is incompatible with Many Worlds! The latter states that the quantum state is real and objective, the former states the opposite.
The QBist horsemen have devoted some attention to the question of compatible quantum state assignments. See: https://arxiv.org/abs/quant-ph/0206110
However, Chris Fuchs does not see any problem in someone assigning a probability-1 belief to a measurement outcome and being proven wrong. See section 2.2 of https://arxiv.org/pdf/1705.03483.pdf
This last point in particular should bring home the point that Fuchs does think there is an ontological theory underlying physics, but that we are fooling ourselves about how much of it is objective/observer-independent.
There is work being done on this sort of thing. If essentially all you care about are the probabilities of certain observations occurring, then you surely can represent any theory with real numbers. The field of "generalised probabilistic/physical theories" attempts to analyse quantum theory without assuming the baggage of Hilbert spaces etc... [0]. Chris Fuchs also has done a lot of work on representing quantum state spaces in terms of outcome distributions over special types of measurements called sic-povms[1,2].
0. https://arxiv.org/abs/quant-ph/0508211
1. http://perimeterinstitute.ca/personal/cfuchs/
2.https://en.m.wikipedia.org/wiki/SIC-POVM