Whitebeard was dying , even if Marineford didn't happen, taking off all those medical equipment was gonna kill him, Marco remarked that taking those off is what made him unable to use his CoO correctly
Rayleigh was dusty as seen with how he was panting afrer a few mins of sword clashing with Kizaru, but he wasn't sick or dying, he still could use CoO and CoA, he also wasn't nearly as huge as Whitebeard meaning that his body wasn't as much of an open target
Rayleigh was dusty as seen with how he was panting afrer a few mins of sword clashing with Kizaru, but he wasn't sick or dying, he still could use CoO and CoA, he also wasn't nearly as huge as Whitebeard meaning that his body wasn't as much of an open target