> Occam's razor would point towards some general misunderstanding on which we have no evidence to reasonably speculate a cause.
Dark matter is the Occam's Razor theory. It explains almost all of the observations while assuming the least.
Why do you assume we have no evidence just because we don't have direct observations? Black holes were a similar phenomenon that we had no direct evidence for a fairly long time even though we had lots of other indirect phenomenon that really couldn't be explained any other way.
The razor is commonly misunderstood.
William of Ockham objected to his fellow theologians inventing things out of whole cloth (like dark matter question mark). That’s the point, not that a simpler explanation is more likely to be true.
The common understanding would have us believe that creationism, being simpler, outshines evolution, or that there is no such thing as a color revolution because the simplest explanation is that the mass protests are earnestly aggrieved locals.
Yours is a common misunderstanding, as well.
Occam's Razor only kicks in when the hypotheses have equal predictive and explanatory power.
The MOND hypothesis does NOT have equal explanatory power with the dark matter hypothesis. As such, Occam's Razor is not relevant.
Maybe you can point me to the "equal predictive and explanatory power" bit in William's writings.