The .270 case design is 96 years old now. It was state of the art when it was brought out.
The .270 Win was already 8 years late compared to the 7x64 Brenneke
Most likely Winchester didn't want to pay royalties to Brenneke, so they "made their own cartridge".
Just make the caliber a tiny bit smaller, so people just can't recut the chamber to the superior 7x64 Brenneke.
"Invent"... then spend a god awful amount on advertisement.
Just like the 6.5 Creedmore did with the 6,5x47 Lapua.
7x64 Brenneke
270 Win