No. Whitebeard never said that anyone else was stronger than him. He simply acknowledged he couldn't hold on to the title forever which implicitly suggests he did in fact believe he was the strongest and that someone would eventually succeed him....but not until he laid down his sword and fulfilled his goal. He still kept shouting "I am Whitebeard!" throughout the war.
BB believed the fruit determined who was the strongest, so seeing as how gaining it made him the strongest, then whoever had it before him would naturally be the previous strongest.
Doffy was talking about WB right up to his death because no one took the throne before that. If it were just "Primebeard" then somebody else would have been standing before or even sitting on the throne already. Doffy could laugh at Marineford because WB was not directly targeting him and was by every indication going to die there. Kaido would certainly show no mercy if he were to come after Doffy.
BB believed the fruit determined who was the strongest, so seeing as how gaining it made him the strongest, then whoever had it before him would naturally be the previous strongest.
Doffy was talking about WB right up to his death because no one took the throne before that. If it were just "Primebeard" then somebody else would have been standing before or even sitting on the throne already. Doffy could laugh at Marineford because WB was not directly targeting him and was by every indication going to die there. Kaido would certainly show no mercy if he were to come after Doffy.
BB ate the fruit and claimed to be the strongest then procceeded to turn tail from fighting Shanks and ran away from Akainu.