I think thats the kicker really, we all recognize now that haki is what the dark king used in the auction house, and also what shanks used on whitebeards crew. But we DONT KNOW that what raleigh used in order to combat Kizaru...

#one thing i do think however is that haki is an ability, an ability to focus ones will. Luffy may have the presence, determination and strength to knock people down with a look, but unless somone shows him how to tap into the techniques it will never reach its full potential.

Now it can be argued that "oh but how can ambition be a basis for techniques" well if you take into account that this is a work of fiction and i cant even think of a long running shonen anime that DIDNT have some kind of secret none real powersource that characters could tap into .... and they ALL created preassure (and its been described that way many times) on the relative opponent. From Naruto and bleach to Hajime no ippo. When you focus on your ambitions you become more determined and can achive things seemingly out of reach.