Nonsense.
Katakuri's AP and lethality fall far behind Rooftop Zoro. That Zoro:
- Cut through Dragon Kaido's scales and made him cough up blood for several panels.
- Terrified Linlin and forced Dragon Kaido to dodge.
- Scarred Hybrid Kaido.
And no flame King was tanking named techniques from Haoshoku Zoro.
The attack that cut King's mask is considerably stronger than Rooftop Zoro's Tatsumaki (and potentially above even the attack that scarred Kaido), and King tanked it:
Anyone that thinks that Katakuri has the AP to significantly hurt King is being disingenuous in the extreme.
You need AP > what was needed to scar Kaido to significantly damage King.