They can't handle the fact that Zoro's opponent is a mosquito compared to Kuzan
so they bring up the right-hand man cover page and the argument of Shiryu sttabing Garp nerfed him
The stab obviously nerfed him. The point of it was to let Garp go down sooner as opossed to having a prolonged 1v1 with Kuzan.
It still doesn't change the feats. If the stab affected Garp's AP then Kaido fans have to deal with the uncomfortable reality that 0.01HP Zoro put a scar on him and outsped him in 1v1 combat.
Characters in anime perform their strongest attacks even when they're at their weakest.
I highly doubt Akainu and Aokiji created that bomb crater in the middle of PH with their first attack, it was probably the fight deciding clash while both were at deaths door.