Someone's goal does not define their inherent potential. Whitebeard just wanted to have a family, but still became the WSM. It doesn't add up.
And Chinjao often gets used as a mean to low ball CoC and it absolutely makes no sense.
Imagine DFs aren't a thing and there is that man, built like a Gorilla, with a headbutt that can splitt an ice continent.
Most guys up to the known top tier probably couldn't have fought prime Chinjao.
He would legit one shot headbutt them.
He simply had bad luck and came across a "greater" Conqueror, who later on became like the Top3 fighter in that era. And that man even had to train like a madman to surpass that fucking drill head.
Put some respect on Chinjao.
And if you reread Baratie you will notice that the chances for Sanji becoming a conqueror's haki user are low.
He has the strength to back it up and he's strong willed, no doubt, but Zoro and especially Luffy were portrayed as different breeds there and that's coming from a fellow Sanji fan.