If a Newtonian model of gravity doesn't "explain" gravity, then neither does general relativity. These are all different models of reality with different levels of model complexity and predictive accuracy, but there's no fundamentally binary difference between them in their power of "explanation" etc.

So new models like "dark matter" or "MOND" are all just different models that model observations better than prior theories but currently have the problem of being difficult to unify with the rest of theoretical physics.