It's amazing how the pendulum swings we went from over valuing calibers, to now under valuing them. There is a difference in knock down power. Yes, a hit in the heart with a .22lr is deadly, accuracy is supreme.
But the statements that caliber/knockdown power is a fantasy amaze me. They are obtuse.

All of you making these statements, you carry .25's or .22lr's right? After all they are just as good right? They go through barriers, penetrate heavy clothing, get through shoulders, forearms etc just as well don't they?

It is a known fact for example the .357 came about because law enforcement of the time needed a better barrier and windshield penetrating gun.

I have J frame .38's, 9mm's all the way up to .44's for SD, each has it's advantages, but I do not carry mouse guns for a two reasons, experience and street results. Am I under gunned with my P228, no, I hit what I shoot at, but .38/9mm is the minimum caliber I'm carrying because I know anything below that is not worth the tradeoff.

Maybe I am arguing semantics in one sense and what you mean is among the varying service/military/police sidearm calibers all are effective. That I will agree with, but my issue is with the blanket statements being made that there is no difference among calibers in "knock down" power, that's just silly. Almost as silly as the term "knock down" power, we need a new term, maybe effectiveness, I don't know, but rarely is a shot person instantly knocked down. The misnomer of the term I agree with.