In-game, killing a high-level Moon Realm existence using conventional methods was a rather long process. It often involved a long chain of quests and a considerable sized dungeon.
Of course, one could also choose to fight the main body of a high-level Moon Realm existence from the beginning, but because this wasn't the method recommended by the game designer—after all, they had designed exquisite and interesting dungeons for these Bosses. If one fought the main body straight away, the resistance of the various stats of a high-level Moon Realm existence would be so high that players would doubt their lives.
Therefore, generally speaking, players needed to enter the Moon Realm dungeon first—extinguish a few lamps that symbolized something, close a few doors that led to a certain source of power, or kill a few guards, save a few souls, and find a few helpers…