That wasn't because the 7.62 round wasn't invented in a European country,
I think that not being invented in
their European country had a bit to do with it, but of course such snobbish bullheadedness doesn't look good in the history books, and yes, we had our own version of that, as well.
The British were working on their .280, their bullpup rifle designs and yes, the idea of an intermediate round was appealing, as even their most stubborn folks realized they had taken the .303 as far at it could go.
the Germans were working on their own designs, one being (surprise) in 8mm Mauser, with other factions working for the 7,9mm Kurz and some for something else entirely...
The French were working on..well, ...being French...
I don't think the US was stuck in the myth that every soldier was a 1,000yd sniping machine, so much as that if they had a round that would do it, they
could be. I think, as much as anything the 7.62x51 was developed so they could make a change, without making a change.
The .30-06 WORKED. It worked in WWI. It worked in WWII, it worked in Korea. And the new round WAS the GI .30-06, down range, anyway.
It always boils down to the actual people making the decisions, their personal beliefs, what they think is the best thing, what they can justify, and what they can get away with....
I can easily envision some Army brass looking at those studies, seeing them showing the intermediate cartridge better suited to modern combat, and setting them aside in favor of what they KNEW WORKED.
Machts nichts, today, other than as history, but don't think NATO or anyone else really operated, or operates differently, today.
Here's something to consider, and a bit more in line with the OP, if you wanted a high speed .30 caliber pistol round why go with the Tokarev, why not use the .30 Luger which fits in everything a 9mm does, and could be "magnumized" to a degree??
I'd be willing to bet, using some level of +p loads and not using the FMJ bullet from 100 years ago, you could do some fairly impressive things and do them from a handgun that the Tokarev round won't fit into.