Not to anticipate his own reply, but as @PdotdQ brought up insightfully several months ago regarding MOND:
In other words, there’s a complex web of evidence that needs to be navigated, and it is hard for one theory to fully resolve all the major, contradictory problems we currently have. At face value, @Joe_Bakhos’s theory seems to be a modification of Newtonian physics, or a version of MOND, so it wouldn’t be surprising if it can be tweaked to explain galaxy dynamics well. But that’s not enough to satisfy astronomers and cosmologists. I think no satisfactory cosmological model has ever been constructed assuming MOND.