Well then a couple more for the sake of your comment:
Lucci was defeated because Usopp was there at Enis Lobby, to remind Luffy that the world isn't hell. In the Water Seven Saga, more than any other story arc, Luffy is given the impression that he cant trust other people. Lucci's character is all about that inability to morally trust other people. He himself is revealed the be a spy and thus ultimately untrustworthy. Moreover, he wants to kill Nico Robin all because he lacks the basic trust that she wouldn't merely blab out her secrets to the first person that threaten her. His dark justice is a pessimistic philosophy. That level of pessimism is not justified though, because as Usopp says: this world is not hell.
Moriah was defeated by his own sail collapsing and falling on him. Moriah's whole shtick is that you cant rely on yourself and that the best way to win is to spend your efforts trying to get the most out of your subordinates. By necessity, this requires a huge organization: the biggest ship in the world. Except, if you're at the helm of this huge ship, but you have no personal strength of your own, what are you going to do when the winds of change start turning another direction and you're the only one trying to resist it? When everybody starts asking for their shadows back? The company can eventually control you, no matter how absolute you think that your power over them is.
Luffy was defeated in Sabondy because he assaulted people and picked a fight that he wasn't prepared to go all the way with, whereas the celestial dragons and the navy, for all their moral shortcomings, were.
Luffy was defeated by Magellan in Impel Down the first time since he was picking a fight against someone he was solidly advised that he couldn't win against and was being inconstant with his previous self and his previous beliefs. Moreover, because in trying to rescue Ace, he was hypocritically ignoring all of the other prisoners like Mr 3 and Buggy. But this time, he was saved by the concept of a miracle. Because, since he stuck to it this time, it might've been possible for him to win that fight if there was a miracle, and thus his decision wasn't all bad.
The second time Luffy fought Magellan, with Mr 3's help, he could successfully hold him off.
Yet Luffy couldn't beat Hannibal, because as many hits as Luffy could get in to represent how bad the prison system is, he had no argument about why people should be allowed to escape. Hannibal, representing the purpose of prisons in keeping villains away from society, could hold Luffy and Co off for Long enough that Blackbeard could appear and one-shot him, which he did because he brought forth the nihilistic concept that there is no consistent moral reason to send people to prison everywhere in the world and therefore the whole idea that certain people should be impersonally imprisioned is inherently arbitrary.
Whitebeard lost at Marineford because he represented Universal Compassion. Akainu, representing a desire to harm people for the sake of justice, wounded him, much like that desire wounds the ideal. And in the end, it was his own crewmates who killed him, showing that, even at the best of times, the concept of compassion doesn't always pay off. Beautiful as it is, there will always be nihilistic jerks who will repay your compassion with betrayal and treachery.
And Ace died because that's the inevitable answer to the question of "Does everyone deserve to exist" in the world that we live in. Fittingly, he actually died to a Darwin award by turning around and picking a fight with Akainu instead of helping Luffy escape.
The entire war was ultimately stopped though by Shanks, who had always in some level, represented that idea that you shouldn't fight at all unless you're prepared to risk your life to kill the other person. None of the players there were quite willing to do that after Ace and Whitebeard's deaths, so they all backed off.
Hody Jones was defeated by being punched through the Noah, a symbol of ancient promise between human and fishman and an enormous proof that they can get along. And by a human, who was undeniably doing it to save fishmen. Given the context he was being hit through, there was no way to delusion that Hody was a hero.
Doflamingo, representing manipulative governance, was defeated by getting shoved out of the sky and through the ground, into the underworld dock he had hidden under Dressrosa. He was a demon, but he didn't deserve to be heavenly, like his title described him. Manipulative people might be allowed to exist, but anyone can agree that they don't deserve to exist at the top of the world. Doflamingo also saw the world through literal rose-tinted glasses.
And Katakuri lost because, though this symbol of high personal expectations could outmatch Luffy in any one area, unlike Katakuri, Luffy was more happy to simply exist, and less hurt in the moments where he did fall.
And for Kaido... Burning in Lava is a parallel for Oden's death I suppose. And Big Mom gets thrown in there too, just for the hell of it.
See the issue?
I hope you found pleasure in this. It took ages to write.
