What if Rokushiki is Haki based?

The Nico Robin: Rokushiki Style Project

Why didn't Luffy learn Rokushiki techniques? - Quora

Vivre Card Databook – Index Set (some new information) – The Library of Ohara

One Piece 1081: Strongest Haki users in One Piece updated ranking

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Who's-Who still hasn't revealed his true strength! - One Piece

Powers & Abilities - New Level CoO + CoA Combination Technique..

Nico Robin haki kick color by xMrNothingx on DeviantArt

Why aren't there more characters who uses Rokushiki? Like if you spend your whole life being a swimming champion only to have to eat a Devil Fruit that throws away those years

Rokushiki is based on physical strength is actually based on a mistranslation in earlier One Piece volumes : r/OnePiece