Restructuring the Nigerian electoral process

Let me paint a scenario for you;
imagine if all the registered party members within the country held simultaneous primary elections to select a presidential candidate.
That would eliminate rigging and all the noise about "bought delegates" and "switched delegates lists"
Each state would give a true picture of the candidate they want.
Imagine a scenario where the winner in the state gets 5 points, 2nd place gets 3 points and third place gets 2 points.
With all the states selecting at the same time there is almost zero chance to rig and the total points candidates get from the 36 states+ FCT will determine who gets the party ticket..

The party convention would become a ceremonial event where the running mate is confirmed and the party flags handed over to the winner and his running mate.