> As a theory, it's quite simple: in its absence, the physics doesn't work. If you add matter that behaves in a particular way, simulations align to observation.
They actually don't, numerous extra parameters have to be added for DM to account for observations. DM was invented to fix one problem with observation, and 15 more have cropped up which don't fit.
See the paper [1] and the discussions of the times DM has been falsified. Extra parameters were then added to account for the new observations, where MOND makes certain parameter-free predictions that match observations. Clearly neither theory is a perfect fit for observations but the strong preference for DM seems unjustified.
They actually don't, numerous extra parameters have to be added for DM to account for observations. DM was invented to fix one problem with observation, and 15 more have cropped up which don't fit.