Sounds like somebody didn’t see all the endings. Seriously though, Yoko Taro loves bullying gamers and there is a lot of painful grinding involved in some of the endings - the scrapyard, flower, and fishing side quests particularly come to mind. Oh, and the one side quest where the item is right outside the door to the final bosses, so you have to go through the final dungeon, backtrack through the dungeon to turn in the quest, then go through the final dungeon again to get to the final fights.
Just over there.