Les...weren't there some "2 hits to neutralize" matches back in the mid-1980s?
I think modern 3-Gun is in many ways 3 or 4 separate sports masquerading as one. Most of the "bandit" matches have (or at least had) their own rules, scoring and structure. 3-GUN NATION moved toward a common denominator based on ease of filming, less need for longer ranges and a more dynamic structure (e.g. speed speed speed). And in this context I believe the "2 hits to neutralize" scoring system was institutionalized not because it was reflective of the Real World, but because it was faster/easier to score.
You could make a case that when dealing with rifle cartridges, 2 hits anywhere will take the aggressor out of the fight (a case I'd probably feel a LOT more comfortable making if the rifle's caliber started with a .30).
I think the balance between accuracy, power and speed has always been a part of the shooting sports, immortalized, if you will, by Jeff Cooper's "D-V-C" acronym. Some instructors drifted away from DVC into the foggier realm of "combat accuracy." There is, unfortunately, a very human tendency to skew away from the things that are hard, marksmanship, to things are are less hard, getting the hits somewhere on the target.
I've always thought the SF guys I've shot with like Kyle are the living embodiment of Brian Enos' dictum of "See what you need to see."
And yes, we're all crank old farts...
Michael B