Marineford thaught Luffy revenge was a foolish thing that will only bring you to your grave (see all the Ace-BB story and also how Ace hot blood made him fall for Akainu cheap trick ultimately leading Ace to his death in order to save Luffy). At that point you felt the story, the threat, everything was great. Then rightly, the post time skip is a walk in the park until he had to face lessr opponents starting from Hody all the way to Doffy (and rightly with Doffy Luffy had to show his true skills to advance). And at last it happens, WCI, Luffy has to enter the HQ of a yonko and on the top of that with only half the crew without both Zoro and Sanji. There is not even Law. He is all alone with the support of weak SH who for sure can help and well but at the same time Luffy has to look after them.. Sobthis becomes a stealth mission and this can not be any other way (even if everybody knows Luffy will wreck the plan). Then Luffy screws everything, has Kata completely trapped but goes back to fight him, Ace lesson is forgotten, at some point even goes out to fight BM (now I don't even recall all the stuff) and lastly, Oda, not satisfied with all the ridicoulous amount of plot power he brought up to make Luffy beat Kata, BM become.an handicap.for her crew, Luffy at the same time rescues Sanji with half the crew and also steals BM red poneglyph he makes chapter 900 (and until that point the hundred mark chapters were inportant) where it seems it is finally time for the payback but nope. It is just a fake tension chapter. Kudos Oda.
This is my take on these facts, anyway I admit that at this point I'm still reading OP mainly for nostalgia (and also keep up with all the ridicoulous fandom wars in this forum lol).