Nobody has ever said that the .22 Long Rifle makes a man-stopper defensive cartridge. However people still carry it for self-defense purposes. Maybe people have disabilities that preclude a more traditional centerfire cartridge for defensive purposes. Others prefer the ultra-petite size and weight of some small pocket pistols. Or there may be budgetary or availability considerations in a person’s life.
No matter the reason, I know plenty of normal people who carry a .22 everyday.