You are completely wrong. Understand, possessing ACOA is better than not possessing, the punches Luffy used to defeat Doflamingo had basic ACOA, that basic COA didn't even scratch KAIDO. INU and NEKO, or even KINEMON do more damage to KAIDO than Luffy's version after WCI, even though they are physically weaker, do you understand the importance of ACOA? The strategy of the MAN who defeated Doflamingo with basic COA was to learn the "Ryou", to bypass KAIDO's durability in order to deal him relevant damage, but it turns out that this also failed, it only caused superficial damage to KAIDO.
If INURASHI tries to pierce DOFLAMINGO's basic protective COA he will get it with his ACOA because he already pierced something more durable while LUFFY's version in DR couldn't get past DOFLAMINGO's COA both COA were the same, if INU tries to pierce the KATAKURI's monstrous COA he's going to get because he has aptly ACOA for it. So JACK's feat of fighting two highly damaging enemies to him offensively is insane, more insane than Doflamingo versus Luffy with basic COA.
Not sure if G3 luffy DR version will be enough for JACK. Alias TOGEN TOTSUKA is killing DOFLAMINGO (the combined attack of the scabbards), in fact KINEMON doing a double attack with Denjirou, INU, ASHURA does not mean that their attack are at the same level, it served to leverage the attack even more, even if the of some are inferior to the others, but it turns out that the result was the same, shallow damage (superficial).
It amazes me to know that TOGEN TOTSUKA from INUARASHI dealt shallow damage to kaido while Luffy after WCI did 0 damage without ACOA and Luffy after UDON in G4 got the same treatment as INUARASHI and the others, superficial and shallow damage, so why Are you underestimating the attack of the sheaths? If even Luffy's big punches after WCI and rigorous physical training in UDON and got ACOA, had the same result, LOL.
And by the way JACK has an incredible feat, he wasn't knocked out by the monstrous TROMBA of ZUNHISHA, which is > Ap of the G4.
It is uncertain whether or not it was, because it was exactly conscious when we saw it underwater.
@playa4321