User blog comment:The ASL Pirates/Height=Power?/@comment-10543621-20150331232634

I really don't think this as anything to do with anything other than Oda's whim when he decides to draw the character. I just means that races in the world of One Piece have the potential to grow to be much larger than real world humans.

I mean, the same size discrepancies are also shown in other races. Most obviously would be Giants. We've seen normal sized giants like Oimo and Kashi to massive ones like Oars and then there's Sanjuan Wolf.

Fishmen and Mermaids vary quite a bit in size as well. The royal family are generally larger, and Shirahoshi is the weird oversized one. She's obviously not strong (unless you count her secret ability). There's also Mdm Sharly as another oversized mermaid. Fishmen wise, you have tiny ones like Pappug and massive ones like Wadatsumi. I guess for them, it kinda also depends on their species.

But yeah, I think this is just the case of Oda wanting to make the inhabitants of the One Piece world vary in sizes more drastically than in real world humans. I guess, in a way, real world humans can vary quite a bit in sizes as well. You have really small sized people about 1.5m fully grown, and you also have the >2m giants that usuallly inhabit the NBA. Oda just stretched the range is all I see.