IMHO more of a marketing ploy then any basis in fact. Same reason Parker Bros. added 28-gauges and later .410-bores to their line -- to sell a new gun to their existing client base.
Shotgun manufacturers are pretty much limited to six gauges to sell and have had to resort to changes in barrel lengths to sell new guns. We could likely take care of all we need in shotguns with the 10-, 16-, and 28-gauges; and get rid of the other three.
Rifle manufacturers can neck it up, neck it down, blow it out, etc. In reality the .22 Savage Hi-Power, the 7mm Mauser, the 30-06 and the .375 H&H can take care of most anything that needs taking care of. Every new rifle caliber since 1912 was likely more marketing than filling any real need.
Enough of my rant!!!
