I've only made it about 300 posts into this thread over the last few days due to time and slow foreign wifi. Here are my thoughts having looked at a good deal of pictures on the mentioned threads.
For background, I shot competitively at an extremely high level through college and have continued when I can in other disciplines. That's not a brag, it just means I have pulled a trigger with intention a lot. That being said, I have missed 3 shots while hunting big game. Two were in my early years of hunting (12-15 years old) and one was in 2020 because I didn't have/take the time to range it and was a good 200 yards off due to terrain and leaving my scope on 10x from the last practice session.
1) Accuracy is the #1 component of killing animals. It doesn't matter whether that bullet performs like a 77gr TMK from a .223 or a 250gr TTSX from a .375. If it's a miss or not in the vitals, you're going to have a bad time. While I can shoot my Service Rifle a scoche better than my .270, I can still shoot my 270 a lot better than many can with a .223. They can practice for less money than I can, but I've got a base of experience that allows me to maintain my skills with less time on the gun. I do dry fire (or play with my toys as my wife says) at least weekly with my primary hunting rifle.
2) Some people handle recoil better than others. I started hunting with a sub-6lb single shot .243. To 9 year old me, that thing kicked like a mule. What I didn't know at the time, was it kicked about the same as my father's 9lb .270 and he probably didn't either. Through a lot of practice (it's fun shooting ammo dad's buying), I learned to shoot that rifle very well. What I say about recoil is that whether you hit your target or miss, the recoil is a constant so you might as well hit your target. An 8lb 300 Win Mag is not fun to shoot but I can still shoot one well. I don't care if I can spot my hit because I can call my shot. If I'm taking a shot on an animal, the first thing I'm doing is running the bolt. I'm preparing for another shot whether it's needed or not.
3) If you're going to shoot a match bullet, know it's limitations. I don't remember many pictures posted of animals shot hard quartering away (entrance in the rear 1/3rd) in those threads. I saw that Form posted above that the 77SMK is good for about 12-14" of penetration which isn't enough to get into the vitals at all angles on all game. You have to be willing to eat tag soup if the bullet you choose is not going to get the job done.
4)
@Formidilosus, if I show up to a guided hunt in grizzly country and my guide has a .223 and TMKs, I'm getting back on the transport. I know your comment was likely tongue in cheek but I want my guide to put that griz in the dirt time now. I don't care how the bear is doing 30 seconds from now.
I choose an 8lb .270 for the bulk of my hunting. My primary reason for this is that I enjoy the cartridge and the rifle and shoot it well. Here in about 5 or 6 years, I will have a .243 or 6CM because I will have two kids coming to shooting age and besides the practicality of having one primary cartridge to load for, I think most kids would find it cool that they have the same thing that dad has.