Newtonian physics works perfectly well as a theory until you move to quantum or cosmological scales. Nothing wrong with using in the correct scope. Theories will always be correct until they aren't, and then (hopefully) new theories emerge which are able to be applied more generally. Those theories will also be true, until they aren't 😉
Discussion
Yes and we should not treat Newtonian gravity as a right theory anymore since we now know by measurement that it’s not, and even when we thought it was, it was reproducible at the known scales. Not sure how this is contradicts what I said previously though.