A precision. The power of destruction of WB was actually introduced very late (in MF). What was hype about WB was his relationship with Roger as he was introduced as Roger's rival. Therefore, WB was a way to have a glimps of Roger's strenght and the ceiling of power of the OPverse. This is why WB was hype at the time. And later, it's not his power, but his durability who created respect.
Careful with the author's note it was contextual, not an affirmation.
In reality, Oda clearly explained who was the strongest man in the world before the death of WB:
Again, OP is contextual. It works with authors note as well. When Oda talk about the strongest here, he talks about the ceiling and the man who rivaled Roger.
So in his prime. WhiteBeard was stronger and Kaido wouldn't have a chance.