it has nothing to do with the validity of cross cultural comparisons it has everything to do with original research and laziness there are all sorts of similarities that exist in the world and all sorts of similarities that some editor is going to think is interesting if we applied the standard you proposed every article could overflow with comparisons someone thinks is interesting that is why reasonable sources are required and items without sources deemed original research i honestly don't understand how you can think a reference is so important but not important enough to take some time out of your busy schedule to do some due diligence hell all you probably had to do was google odysseus and ramayana