For arguments sake (and I highly respect your opinion), why don't you see cartridges like the 30-06 or 243 win dominating any benchrest sports, is it simply because they have more volume and burn barrels out quicker, or is there something inherently more accurate about shorter stubby cases with steep shoulders as found in the PPC and BR cases?
The .308/7.62 is not superior to the 30-06, it is inherently more accurate because of its shorter case length which helps with alignment with the chamber and powder burning efficiency. This was proven with the changeover from the M1 Garand to the M14 military rifles.
Now you can call me a cheap bastard if you want, BUT with the recent shortages we have had with reloading, "WHY" would you want to fill a monster case with that much powder when it takes only half this amount for the .308/7.62?
Due to an injury at work I stopped hunting but still love to shoot, and I spend all my time with the .223/5.56 because its gas tank is small and it gets great gas milage.
So just remember this, when dealing with monsters all it takes is a head shot to bring them down and you don't need to own a powder company to do it.
The only advantage you Canadians have is the fact that Zombies freeze during the winter so you have the winter months to restock up on powder. In the lower 48 we "normally" have milder winters so a .223 loaded with 25 grains of H335 of powder gets us twice the shooting you will with a 300 WSM. (powder/gas hog)
And below for Eagleye the smartest one in the bunch. 
From the "The Rifleman's Journal" http://riflemansjournal.########.com/p/articles-index.html and shooting 1000 yards with the 30-06.
Cartridges: Accuracy Secrets of the .30-06 - Part 1
http://riflemansjournal.########.com/2012/05/cartridges-accuracy-secrets-of-30-06.html
Cartridges: Accuracy Secrets of the .30-06 - Part 2
http://riflemansjournal.########.com/2012/05/cartridges-accuracy-secrets-of-30-06_10.html
Cartridges: Accuracy Secrets of the .30-06 - Part 3
http://riflemansjournal.########.com/2012/05/cartridges-accuracy-secrets-of-30-06_13.html
Cartridges: .30-06 Update
http://riflemansjournal.########.com/2011/02/cartridges-30-06-update.html