Do I really need to?
If the Courier has the ability to conquer to armies in one fight, the Lone Wanderer has the ability to take down a huge chapter of BoS, or nearly eliminate the East coast Enclave, all of the things that The Chosen One and Vault Dweller do in FO1 and FO2, a human in real world can singlehandedly inspire revolution, compromise, rebellion, etc. What is to stop the Courier to complete yet another amazing feat?