Whitebeard and who? Unfortunately, King disagrees with you.
Kaido himself only sees them as capable of fighting against him. Even Whitebeard avoided fighting Kaido in Wano, and Whitebeard is equal to Roger... Oda isn't showing respect to Roger and Whitebeard when he chooses to elevate Kaido as the embodiment of strength, something Roger is not, and has King tell Kaido to continue being the strongest there is.