If a Yankee has a 9.3x62 does he still have to own a .35Whelen?
Not if he is smart. The 9.3x62 is a better round. The truth of the matter is there really is no reason for the Whelen to exist. All he did was take the 30-06 and neck it up to 35 caliber. The 9.3x62 is basically the 30-06 necked up to 36 caliber. You can make 9.3x62 brass by running 06 brass through a sizing die, fire-forming it and trimming it. Whelen solved a problem that had already been solved decades before.
For what it is worth, the 30-06 cartridge is based on the 30-03 cartridge which was in turn based on the 7x57 Mauser cartridge. The Springfield Model 1903 rifle's action was so similar to the Mauser 98 action that Springfield was required to pay royalties to Mauser until WWI broke out. Germany is responsible for a lot of great rifles and calibers.
