I don't think you understand the concept of explanatory power. Because dark matter cannot be observed we must manually tune the dark matter distribution for ea

I don't think you understand the concept of explanatory power. Because dark matter cannot be observed we must manually tune the dark matter distribution for each galaxy. This creates new parameters that don't exist in the theory that are necessary to properly explain phenomena. Whether or not they exist in the theory is irrelevant to the fact that they are necessary.