WHY WHITEBEARD NEVER USED KING’S HAKI IN MARINEFORD

As we all know Whitebeard had CoC but why didn’t he ever use it? I mean Luffy was a complete novice in CoC but when he used it he knocked at least half the people in Marineford out; if WB had decided to use CoC at that exact time, i’m certain he would be able to knock out anyone below vice-admiral level. But why didn’t he use it?I believe that he was using CoC the entire time. Why didn’t he knock anyone out? I believe that is because Whitebeard was using it to conquer his own death; i believe that the wound Squardo gave to WB was actual fatal and WB was actually using his haki the whole war to delay his death. Now this may seem a bit far fetched but it actually makes a lot of sense; i mean Ace’s mom could hold in a pregnancy with haki so why couldn’t WB conquer death? This can also prove why he didn’t use haki to knock anyone out, as doing something like conquering death must be insanely difficult and would probably require a lot concentration. Also, there were many times during Marineford where WB actually said that he planned to die in Marineford

-why would WB allow buggy to kill him?
Not to mention this