Haki is complete ass. The only type that was actually interesting was Mantra/Observation haki. The only purpose haki seems to serve as to nullify devil fruits but there were already decent alternatives to it before the timeskip, like seastone, salt or actually throwing your opponents into the sea. It doesn't help that the ability is portrayed so inconsistently or that you have characters with AdCoC always forgetting they have it. Even Luffy training to master the yakuza's new haki technique in Wano feels pointless.
Dude none of that shit would work on high level opponents.
WTF is salt going do vs logia admirals or warlords and throw people into the sea when the fuck has that ever work since fights mostly inland LMAO .
Fucking luffy run the whole first half manga cause smoker had no weakness .
Sure haki inconsistent in how it done but not like that matter in this arc since you can't hurt the elders .
Luffy using ACoC or not don't fucking matter when these people get cut apart and it don't mean shit .
Every power up is pointless this arc cause you can't hurt the elders even with G5 , haki or what ever else.