Is it a problem that he mastered 3 haki types after fighting a yonko? Then show me who koby fight to unlock to Advcoc . The devil fruit issue has become really boring, it's not really a problem, you don't even realize what you're asking for, you sure about luffy not being able to beat kaido before devil fruit awakening, and now you're bashing the fruit awakening "how can luffy's fruit be special", you ignored the real problem, kaido's power was unclear, was increasing and decreasing it as Oda wanted, so a lot of things got messed up.