@Count:
I love seeing superpowers thematically parallel a character's personality, background, and aspirations in some way. But I think this giving Oda too much credit when it's clear that most of the Devil Fruits he assigns are either due to fun concepts, reference some type of media or history, or plot devices. So I still believe Oda's explanation on the Volume 65 SBS in that he wanted a protagonist who could look and act goofy to stand out from stoic heroes and enjoy writing zany scenarios. I don't think Luffy vs Enel was deeper than taking advantage of a scientific fun fact and exposing the vulnerable hubris of both Logias and god complexes.
As for Katakuri, I think Oda just felt like finally giving Luffy a mirror match. He could have done it with Bellamy, but wanted to make that all about dreams. Devil Fruit redundancy superiority has unfortunately become a trend too. Add in the food theme of the Big Mom Pirates and there you go. Although I do wonder why Oda wanted a mirror match now of all times. I still feel like it's a bit random for this one time enemy/eventual ally to have a power similar to Luffy's especially when what makes him dangerous is moreso his Observation Haki. Villains that have similar powers to the heroes are usually a lot more recurring and personal to them. Blackbeard is the type of character I would expect to have such a Devil Fruit parallel, not token femake Yonko's pseudo-First Mate that only shows up in one or two arcs.
I think Oda once said that he doesn't hide themes in his story. One Piece has obvious moral messages and scene parallels, totally. But I don't think he goes THAT deep when it comes to symbolic representation without making it really in your face. Like how obvious Doflamingo's Devil Fruit represents how he manipulates people like servants because of his superiority complex.
I still fail to see how darkness and earthquakes are visual metaphors for Blackbeard that run deeper than "he's bad so he needs evil/destructive-looking powers". Darkness' negative connotations speak for itself (and it MAYBE emphasizes the black in Blackbeard for clever wordplay) and the quakes are likely inspired by frequent occurences and social anxiety in Japan with natural disasters like earthquakes, making it a fitting choice for being the strongest Paramecia Devil Fruit.
So all in all, I think that theory is… a stretch, to say the least. But props to somebody thinking outside of the box like that. I love seeing people analyze potential themes in a story even if they weren't intended by the author.
At first i thought so as well but considering Oda has done this a few times actually, sometimes more sometimes less subtle, i actually do not think it´s too far-fetched.
Luffy vs Enel is the most obvious one really. He literally has Enel state that he is a god and also has him state that the term god is equal to fear, and the Skypeians are not free due to their fear of Enel, and Luffy liberates them.
It´s symbolism 101 really.
It´s a mirror match, certainly, and both are heavily respected by their crew/family respectively. But for Luffy the respect is based on his actual personality, for Katakuri it is once again based on the image his siblings have carved for him and he is simply following that.
Now for the first time, he is doing something for himself openly, instead of hiding behind closed doors and eating donuts.
And the match was never about DF superiority but Katakuri´s supposed superiority which has been debunked by this fight.
It seemed like it at first, no question, with Katakuri trying to hammer in the point that he can do anything Luffy do, only better. But that urge of his was replaced by his curiosity to where Luffy can go and whether he can be an actual opponent.
The first was befitting of his image taht his siblings had of him, the way he is fighting now is for himself.
Nah, that statement has been taken out of context. Oda practically says that he is not forcing anybody to take a certain message from him and that that is the only interpretation but that he lets people take away what they do from the story, despite Oda having things to say himself and aiming for a certain "answer", as he himself put it.
But the Enel thing is not really different from DD when you have the character itself terrorize the citizens and then declares himself a synonym for fear, pretty straightforward and in your face really. Same as Toto´s determination surpassing Crocodile´s despite having no physical power at all and that that determination and lack of doubt, which led him to collect the water, ultimately also leads to Crocodile´s demise, since that is what allows Luffy to recognize Crocodile´s weakness.
Oda does write and articulate this stuff tangibly in the manga if you pay enough attention to what´s said and done, but sometimes it is overshadowed by more superficial highlights.
Blackbeard i don´t know yet but BB not falling under that pattern does not detract from other antagonists doing so.