It's not about declaration, if it was a simple declaration said only ones then I wouldn't give a shit. But it's a 10+ year running plot line with a STRONG narrative force behind it, and even a lazy author like Oda wouldn't build it for no reason.
In middle of Wano we go to marijoa when we found out that Garp got all the credit for taking down the most powerful pirate crew Rocks. And then the Rocks come back where Garp's grand son is fighting against them.
You think this is also something that happened just for fun? Kid will damage Meme but he will not take her down, it's going to be Luffy, at least that's how Oda wants it to be.