Again there's no DF + Haki user at the same time.
Except Zoan types like Kaidou and Luffy.
- Bigmom
- Law
- Kidd
- Whitebeard
- Fujitora
These people fruits are not meant to be used with Haki.
Yes bigmom and Whitebeard had AdCoC but how many of their attacks were actually coated in haki?
There's Basic Haki to hurt DF user. Which doesn't work like multiplier
Then there's, Hardening , AdCoA , AdCoC which Amplifies the Damage.
Yamato Power arsenal had to similar to Kaidou and Luffy or else. She would have not survived in the longer run.
So even Law , Kid , Fujitora were the types to have CoC / AdCoC. They will be relying on fruit much more than Haki. That's the domain only few takes where DF is compatible with haki.
Like Doflamingo , Katakuri types.
Roger Only had Haki up his sleeves. And swordsmanship.
Whitebeard had Similar haki and similar grade weapon and an OP df on top of that.
Whitebeard should be a tier above looking at the paper skills.
But he isn't, he is either equal or Stronger by a bit.
Luffy , Kaidou , Yamato DF aligned with how Haki is used and hence they trained and Amplified it.
Law power cannot use Haki amplification
Kid powers cannot use Haki amplification
Bigmom Powers cannot use haki amplification
Whitebeard Powers cannot use Haki amplification.
Fujitora fruit Powers cannot use Haki amplification.
Because how the fuck do coat , Space , Magnetism , soul , Viberation , Gravity in haki?
You simply can't.
They can only use Haki alongside it to attack a DF user which won't be working as an Amplifier but only a medium through which their Attacks even land on Logia Types.