Probability theory doesn't "intrinsically favor" MWA over ORSA. Both have their uses, their limits, and their "gotchas" when applied to bounded rationality. If MWA is in some important sense "reliably better" than ORSA, I'd need stronger evidence/argument than is provided in this post.

• It's true that both MWA and ORSA break down badly in certain, non overlapping, contexts.
• I currently believe that MWA generally produces better predictive models about the human world than ORSA does. The context of the human world is a special one, and I would expect ORSA to systematically be better in some natural (not necessarily mathematical) contexts.
• I believe that ORSA does outperform MWA in certain situations involving the human world (c.f. the remarks in my other comment about bubbles).