Knock Down Power! BS or a real thing?

"Knockdown Power" is an unfortunate misnomer for what is actually going on. And, every video and article on this topic completely sidesteps the one source of evidence that would settle the question: people who have been shot!!
The phenomenon should have been called, "Startledown Power" or "Shockdown Power". It is partly the physical energy imparted to the victim/perp, but even more, the physical reaction to the event. Nobody really gets knocked down, but lots have a reaction they might interpret as being knocked down.

In all these discussions about what caliber to use, I came out with a simple conclusion: carry what YOU can handle. If you can handle a bigger caliber as good as your friends can do with a weaker one, what is the point in going lower? Capacity, cost, easy of concealment, if you can go with a bigger one, will that be worse for you in a firefight? Of course not. A firefight is not about who is right, but who is left standing...

And people should remember of the aftermath. You will be seeing the inside of a courtroom, no matter how much you claim it was self defense. And you can bet your sweet ass a prosecutor will pick on how many shots you did. If it take more rounds of a lower power caliber to bring down a aggressor, do you think they will not twist that against you, saying you had the intention of killing, instead of just stopping the aggression? Every detail counts in a lawsuit, so the better you can make your case, bigger the chances will will not meet the buddies of the guy you shot behind bars.