After the invention of GPS, aviation increased its capabilities due to the advantages GPS provides. Many modern flights depend on those capabilities to be economically viable, and are thus dependent on GPS.
Simply because it’s possible to fly without GPS doesn’t mean it’s commercially viable. Remember, before GPS, direct transatlantic flight weren’t generally possible because there’s no radar or radio coverage out there to help with flight navigation. Also for a long time, plane navigated by flying low and literally following giant arrows on the ground[1]. I doubt anyone is particularly keen to return to that kind of navigation.