Historically, the way cartridge development went was that the first military cartridge rifles, firing black powder cartridges, were fairly long (had to be, to hold enough powder to make the heavy bullets move). When smokeless powder was invented, the cartridges shrank in bore size, but not a lot in length, because the infantry was expected to engage it's foes at long range (800+ m) and the machinegun hadn't really been incorporated into the infantry yet (they were a support weapon, at best, and might not be available at all). The Spanish-American and Boer Wars encouraged this thinking, showing countries that shorter, less powerful cartridges were inferior (though some of the inferiority was more due to the rifle than the cartridge). During WWI, on the Western Front anyway, it was found that the long range of the pre-war was really not needed when there were MGs around, the MGs could deal with the targets at long range and a less powerful cartridge would be easer to shoot for the less trained conscripts who filled out the armies. Historically, nothing came of this knowledge until WWII was rolling, though at least some of the combatant nations did studies and the US almost adopted an intermediate cartridge (the .276 Pedersen, which was rejected for the M-1 Garand only when the top General of the Army (Douglas MacArthur) said the Garand should be redesigned for the older .30-06).