I still have the .25 caliber Baby Browning that my late father carried as an ankle gun when he was a police detective in Birmingham, AL back in the ‘50s.
Fun to shot, but probably wouldn’t stop much. When I asked him about that years ago, he said, “Yeah, but it would sting like hell!”
It might have helped that he was drilling out his own hollow points.
Lots of Army officers carried the .22 Short S&W revolver during the Civil War. It held 7 shots.
Most .25 autos hold about 7 shots.
Most of the time, having a gun is far more important, than what gun you have.
As others have noted, there are millions of .25 acp pistols still in existence, still working.
There are a fair number of .25 acp revolvers, over a hundred years old, made in Europe, before WWI.
The cartridge isn't going anywhere for a long time.