As Geo. Herter loved to say, "put sights on the typewriter and you can hit about anything at any distance..."
I grew up on Old Jack O. Not until his passing did I appreciate that he was in the ROTC/Nat. Guard in/during WW I. Yes, he "grew up" to teach English in Pacific NW colleges. No, I have no handle on his finances. At the same time, the .270 was intro'd in 1925 or 1926 depending on who you care to listen to. POINT: From day one it worked at 55K CUP in the old system. .30/'06 was standardized earlier at the current standard THEN, 45K CUP.
You can always spot the "shallow." They assert that the .270 is in all regards vastly better than the old, tired .30/'06. Shallow. Factory .270 ammo will outperform the '06 FACTORY AMMO!. SURPRISE??? Handloaded? You want the slightly better ballistically 130 gr / 140 gr bullets at slightly higher velocity and slightly less recoil or you want the possiblity of heavy bullets, 200 grains plus???
As he admitted quietly, the idea was to take a .30/'06 case and come up with a round that recoils less and reaches further with less drop... In those days, Uncle Sam left fired '06 brass lay and it could be had free or for very little... Surplus ammo, out of date--of course, went for a whole $0.01 per round... at least it did with a surplus Springfield '03, walnut stock and a whole $18.00 or was it $18.50 left on your front porch by REA (Railway Express Agent). Common talk in NRA old magazines, etc. Not too challanging to unscrew the '06 barrel and screw in a .270 barrel... No other gunsmithing required...
When you compare the other "standards" of the day... .303, either; .250 or .300 Savage also standardized at 45K CUP; .30/30; .25/35 WCF or .25/36 Marlin (the same, ha, ha, ha); 7x57; ... no doubt the grandfathers clung to their old standards... .45/70; .45/90... .38/55 or .38/56... .44/40; .38/40; etc.
I had a dear, old friend, retired gunsmith telling me years ago (and he owned several .270s) that before WW II, the .270 was little better than the 7x57 (and surplus Mausers were even cheaper). It was the introduction by B. Hodgdon of 4831 surplus ... owners of '06s were disappointed, but the .270 really learned to sing...
Now the common competition today... .308, 1955; .243, about the same; 7/08 don't recall; .260, very recently; and the .280... it came out in the 1970s. And it was not loaded hot for reliable use in the semi autos and pumps... reportedly... Roughly 50 yrs. after the .270 entered the market... and to a lower pressure standard... I am grateful to Remington for the .22/250; .25/'06; etc. but this was not a market triumph.
The .270 is so close to the potential of the 7 Rem. Mag... and still ... It is like the bi plane crop dusters little improved from the planes basic design of WW I. Lots of "lift and handling." Still gets the job done. So you "pays your money and you takes your choice." Nothing wrong with .308 but the .270 was doing about the same job 30 or 40 years before Uncle Sam decided to put a longer neck on the .300 Savage (which gave shooters original .30/'06 performance in a lever action) and work it at a higher pressure and civilian gun makers decided to make it possible for civilian shooters to use the suplus brassss... again... if you like history... most don't... oh well.