But if you think Loki's leaving Elbaf stronger than Luffy then you've not been paying attention for the last 1170 chapters, simple as that.
No, it’s you who has not been paying attention in the slightest. At absolutely no point in this manga has Luffy left the arc as the strongest character, I don’t think this has happened since like, Arlong Park.
Was Loguetown Luffy stronger than Dragon?
Was Little Garden Luffy stronger than 1.8 billion Dorry and Broggy?
Was Alabasta Luffy stronger than Smoker and Ace?
Was Jaya Luffy stronger than Yami Teach?
Was LRLL Luffy stronger than Aokiji?
Was Enies Lobby Luffy stronger than Garp?
Was Thriller Barc Luffy stronger than Kuma?
Was Shabondy Luffy stronger than Rayleigh?
Was Amazon Lily Luffy stronger than Hancock?
Was Impel Down Luffy stronger than Magellan, Crocodile, Jinbe, or Ivankov?
Was Marineford Luffy stronger than Whitebeard?
Was Punk Hazard Luffy stronger than Kuzan?
Was Dressrosa Luffy stronger than Fujitora?
Was WCI Luffy stronger than Big Mom?
Was Wano Luffy stronger than Kaido?
Was Egghead Luffy stronger than Emeth?
What is this mythical manga you are reading where Luffy always winds up as the strongest character? Oda has already set the precedent with characters like Hancock and Rayleigh being Luffy’s cheerleader despite being much stronger than him, what manga are you reading sir?