What should have happened if Oda hadn't made such a messiah out of Luffy.
Let be honest Primebeard and his crew wasn't even needed. Oden just should accept the help of Rayleigh and the Roger pirates back then that dumb ass. Momo did what his dumb father couldn't do, if he would accept the help of Rayleigh and co,Kaido,his crew and Orochi would get murdered.
Oden and Rayleigh>Kaido
Gabban and Roger pirates+Scabbard would destroy Beast pirates.
As you see Primebeard was not even needed, Rayleigh and Oden could easily do it on their own. With Rayleigh around, Oden wouldn't get fall into the trapp and Kaido would lose two both.