On the other hand, have you ever heard anyone say, "I was in a gunfight, and I just had too much firepower." Is it possible that you didn't hear people complain about using too LITTLE firepower BECAUSE THEY DIDN'T SURVIVE?
If the deterrent effect of pulling a gun is so effective, why carry a real gun at all? Just carry an airsoft gun and depend on that to change the bad guys mind. Or carry a gun with no ammo. If it's all about the shock effect, it doesn't matter, right?
All handguns suck. They are compromise of portability and firepower. We carry them because it's not practical to carry a rifle everywhere. (For most of us.) The most common result of a person being hit with a handgun is that they will RUN AWAY. this means that they are also capable of continuing to try to kill you. In saying that a little gun is good enough, you are basically saying that you think that you are already well-enough protected with a handgun, so it doesn't matter WHICH one you use.
I don't like this at all. I feel that if it has come down to using a handgun to fight for my life, I don't want to pick the ones at the very bottom of the list for being likely to stop the bad guy. Sure a .22 MAY work. So might a knitting needle to the jugular if you can get close enough to make sure you place it right the first time. The FBI has test protocols that determine some rounds are more likely to penetrate enough to stop an attacker than others.
And it's not just the effectiveness of the bullet. Smaller guns are harder to hold well, and harder to aim. They have less weight which means more felt recoil. It's like saying, "When I am fighting for my life, I think it's ok to use a less effective round, fired from a shorter barrel, with less velocity, shorter sight radius, poor follow-up shots, and smaller magazine capacity."
Carry what you want. Yes, it's......technically a gun. But for me, and anyone I know well enough to care if they live or die, I will do everything I can to persuade them to carry a 9mm or larger, even if it means loaning them one until they can get their own. There are narrow exceptions where I will say to go ahead with the .380. Just understand, that if you are carrying a smaller gun for convenience, it is YOUR responsibility to make sure that your training can cover the deficit. If you are an expert who knows that you can handle it well enough to save your life, well then go ahead. But if you are just carrying a little gun because it's more CONVENIENT, I am going to go out on a limb and suggest that you are probably too lazy to train well, and just kind of hoping for the best.
But in either case, it's not MY keyster you are shooting to save.