it's called having media literacy
oda ain't gonna tell you that point blank. he will just make it so.
the mc is set to surpass every pirate. of course others of his generation will also do similar shit. Trope as old as literature itself. But suddenly one piece is not gonna adhere to it?
one piece is the definition of generic lol. if you think ¨the new generation will surpass the old¨ won't happen, you have way more faith in oda than he deserves.
I'm not saying this cause of agenda or whatever. i don't think new gen like Loby should surpass old gen. But it's gonna happen regardless.
Only the MC will, maybe 1 or 2 other characters will. No shonen actually has everyone from the new gen surpassing the old gen btw, even Naruto, which makes it an explicit theme has Eos Gai being like>>>>>>>>>>>>>>>>>>>>>>>>>>>>>eos Lee.
And Oda wanks the old gen more then any other shonen writer, we are like 30 years in, and he´s *Still* wanking old gen. We got old Gaban looking better then young Sanji, let alone the flashback. Only Luffy is definitely surpassing Roger/Shanks, and if he gets help against Imu, he might be weaker then even Joyboy who was up against Imu and the 19 kings and like 99 percent chance got Oden´d. Teach is a wild card and will probably end up surpassing Rocks, and who knows who the fuck Davy Jones is.
Zoro can end up above Rayleigh only through the technicality that Mihawk should be above Rayleigh as a swordsman. The only problem though, is that Rayleigh looks significantly stronger then Mihawk anyway(with Rayleigh stalemating the strongest admiral, coming out looking better, and making the strongest yonko shit his pants and run, while Mihawk runs away from Vice admirals, freaks out at the idea of fighting Yonko and barely looked better then Vista in a stalemate)
Sanji could end up above Gaban, but we don´t even have a way to prove that, so I think they end up around the same level unless prime Gaban is revealed to have lost to someone. Koby has no chance of surpassing Prime Garp though, and Momo would be lucky to end up above Kinemon, lol.