So I'm going to distill it down to this. Frankly, that question is very much in my wheelhouse. Is that the conversation you want to have?
BLUF: IF the question you really want answered is "are these fundamentals relevant" the answer is yes, but in a limited number of engagements and often with rapidly diminishing returns.
The shooting is generally the easiest part of the equation for civilian concealed carriers, the shots are not technically challenging, and the opponents are not particularly dedicated to the fight. Literally 100% of people who disguised their drawstroke, presented a functioning weapon, and fired it won in one-on-one street robbery and home invasion encounters. In those situations, technical skill was largely irrelevant as even a miss was good enough. Many won without even firing, the simple act of drawing put the bad guy to flight. Technical skill irrelevant.
Many of the losses were due to presenting a non-functioning firearm. Empty chamber, a manual safety that wasn't disengaged, or just a POS gun. Again, technical skill irrelevant. More losses were due to being entangled and never getting a chance to fire. Technical skills with the handgun irrelevant. Either side that shot from ambush pretty much always won. Not technically challenging. Some losses could arguably have been wins with better technical skill, particularly multiple attacker situations, although I'd argue that things like getting off the X were more likely to matter than better shot placement as no matter how fast you are, you can't down three spread out guys before one of them can react and pull the trigger. Most of them shot and then fled or even fired while fleeing, so being a harder target to hit would matter more than getting better hits on the first guy. Side note, a really nasty knife injury to the first guy was very demotivating to the remaining attackers universally. Pizza delivery driver, three armed suspects, "victim" uses a doorway as a funnel for them to approach him and literally guts the first guy while dropping down to use him for cover. Intestines do a jack-in-the-box impression. Other two dudes remember they left their ovens on. That same driver had shot and killed a robber a few years prior. I started calling him "Smallpox"...
LE shootings, it varies but you will find more situations where technical skill matters more, due to longer engagement distances, smaller target areas due to cover, more dedicated attackers, and the likelihood of being ambushed. Of the four officers killed on my department since my hire date, none were due to lack of technical skill.
1) Dead with handgun in holster, ambushed on a traffic stop
2) Handgun in hand, shot through the armpit and into the heart from ambush (still managed to get rounds on bad guy before bleeding out)
3) Handgun in hand, shot by long gun with a "bystander" blocking the officer's view of the gunman
4) Dead with handgun in holster, shot through a wall
Officers shot but survived
1) Shot during a foot pursuit from ambush, survived but career ending
2) Shot in a drive-by, relatively minor injury
3) Shot by friendly fire during a surprise knife attack, vest caught it
4 and 5+) SWAT officers have taken rounds during entries from barricaded suspects in unknown locations. At least one shot through a closet door.
6) Shot with his own gun after an entangled draw while being blinded by the suspect gouging the officer's eyes.
Only one of those, the friendly fire incident, did technical ability with the handgun come in to play and arguably a tactics failure was the reason it did. That said, some survival has been due to luck as the officers missed but the bad guy fled or surrendered anyway. In the hypothetical realm, technical skill could have changed the outcome but in reality it did not.
While I'm pretty much 2nd string on the JV as far as gunfighting goes I'm not dead or in prison so I've done pretty alright in the situations I've been in. Without exception, decision making has been the chokepoint in the processing game, not technical ability. I've gotten into one "quick draw" contest and that's because I was an ignorant rookie doing ignorant rookie things and only catching the targeting glance let me get ahead of the game and start my draw before him. He got tangled in his shirt and I had partial cover and a clear headshot and he surrendered. That's the one time draw speed mattered to me, and even then it was reading body language that got me ahead of the game. The one time I had to pull the trigger it was a pair of torso shots from maybe 2.5m on a suspect I'd flanked who was bringing a gun to bear on other officers (and had already shot #2 on the shot but survived list above). Not challenging, and I cheated by using a rifle. You could argue correctly that had other officers had better fundamentals he'd have been dead before I was in the position to shoot him, though, he'd been shot non-fatally already. Even then, decision making was the chokepoint as I had to recognize he was a threat again and decide to pull the trigger. I'd had him in my sights for a length of time at that point, as he played 'possum until the arrest team got up on him.
Foot chase of one of two armed robbery suspects, suspect runs through a creek, gets his foot caught in the mud and flops over on his back. It's dark and the only illumination is from a fairly distant streetlight and my also fairly distant headlights/overheads. This is pre-WML and the flashlights were the big whacking kind, not the little LEDs you can run with in your hand easily. He started a classic AIWB draw. I started my draw, had my sights on him, and was taking the slack out of the trigger when I realized it was a cell phone. I came within tenths of a second of sending a round into a teenager for being stupid and pulling his cell phone out to save it from going in the water. His partner had the "gun" which was an airgun. It is very easy to "out drive your headlights" and have technical ability that is faster than your ability to observe and make decisions. In that day, I'd have had to live with the guilt and the civil suit but probably wouldn't have been charged criminally as it was a solid 'furtive movement' shoot had I fired. Today? Even worse.
So, if the question you really want answered is "are these fundamentals relevant" the answer is yes, but in a limited number of engagements and often with rapidly diminishing returns. They alone are a poor predictor of who will win or lose. I can guarantee you #1 on the fatal list would have scored very highly in any of the metrics used for handgun proficiency. He was my friend. NYPD saw no correlation between range scores and street survival over several decades of record comparison. One could argue that means their range scores measure the wrong thing, though. I personally find that departments that take handgun training seriously also take force on force and other decision building training seriously at least locally. I know which was of more value to me. Yes, I know not mutually exclusive...but nobody has time to do everything they want to do and nobody starts out an expert in all aspects. What I find is, typically, guys who are very technically proficient believe that it is of more value than it is, the same way that gun toters in general believe they don't need a hand-to-hand game because "I'll just screw the barrel in the guy's ear and pull the trigger" sort of thing. They are winning a lot of imaginary fights and since they've never had to be in a real one that challenged those assumptions, they don't know any better yet. That thought process is also fed into by the edu-trainment industry. Realistic FoF is not sexy, and the opportunities for open enrollment students to find it are very limited. @
SouthNarc is likely the best source, and a lot of gun guys won't take his classes because of the hand to hand component. I suck at hand to hand, (as SouthNarc will attest to) and found that class to be of immense value. Knowing when to draw and how to do so while entangled is not going to always be relevant, but I've seen some folks who were pretty technically proficient lose because they didn't have that onboard.
Military engagements are obviously a completely different animal in terms of distance, cover, number of opponents, the ability to surprise the opponent, etc. I'm not the guy to talk about handguns in that context but it would seem likely a very high level of technical proficiency would be desirable and would likely matter more and more often in more situations.