I wouldn't necessarily want to be on the wrong end of a thrown rock, but that doesn't mean I'm going to keep a pocket full of rocks for self defense either.
A factor to consider when you're quoting statistics - how many of those homicides committed with .22LR firearms were done with rifles and not tiny pocket pistols? Because that's the only SD context where the 22 has an advantage over any other cartridge commonly used for defense - concealability.
One other point - we all know how important shot placement is - yet that is the hugest compromise you'll make in a pocket pistol - the sights tend to be crude, the pistol doesn't tend to fit comfortably in the hand, and the sight radius miniscule. Throw in the adrenaline rush you'll be in the full throes of, and tell me how accurate you'll be.
You know, we can each of us buy and carry whatever the hell we wish to use, and if something in .22LR is what floats your boat, fine - but it is a grave mistake to suggest that it is a highly suitable cartridge for the task, at least from a terminal ballistics perspective.
If I had only a .22LR to defend myself with, would I use it? Sure. Would I wish I had something more substantial? You know it.