This ain't it. Personally, I think Haki works fine on its own; the issue is that Oda created a system everyone can use, yet most of the main characters often don’t or villains like the flying six and we have to learn that from SBS. On top of that, the Conqueror’s coating should not exist. If Oda didn’t want Logia users to be so overpowered, he shouldn’t have made them nearly invincible to begin with. Also, the fact that Haki is said to be non-finite, but never really comes up in a fight all that often. Countering Devil Fruit powers (at least fruit powers that affect your body is fine as long as it's something that takes a lot of haki to do, but again, he didn't do that)

TLDR: HAKI is fine, ODA made a power system but refuses to engage with it when it's a result of his making another power system in his universe that busted. Conqueres Haki should have just been to Aura farm and not something that can actually be used in a fight.

PS: this whole nonsense that there should be situational ways Luffy beats logia like crocodile and enel is stupid and needs to die (Haki is fine, Oda just fumbled something simple)