There is no power inflation bullcrap. People just don't fundamentally understand One Piece. There's a balance of power there, unlike Dragon Ball.
Luffy beat Croc, Enel, got G2/G3, did a whole bunch more shit, and Croc was still more impressive than him in MF. And he literally gained 0 new abilities. Same ability. Same old Croc. It's not like he got some advanced Haki.