A few hundred years ago you could happily put a character in a saga and have them go off on viking raids and kill any number of people whose only crime is living near the coast, and still put them forward as morally admirable.
Nowadays if you want to have your protagonists shooting at their enemies or hitting them with sharp bits of metal you basically have to choose between a good-vs-evil narrative or having only anti-heroes rather than plain heroes (and both choices are now common).
So I think this bit is pretty much backwards: « Good guy/bad guy narratives might not possess any moral sophistication, but they do promote social stability, and they’re useful for getting people to sign up for armies and fight in wars with other nations. »
What modern Good-vs-Evil narratives are collectively yelling at us is the idea that _only_ outright visible evil justifies making war.