ELT's do find survivors
In the US, Civil Air Patrol occasionally finds survivors from an ELT activation. In fact, ELT's tend to fail with crashes bad enough to kill all on board.
I remember one a few years back where a helicopter crashed in bad weather in the mountains of Southern Arizona. Our team was able to locate the ELT using its in-flight direction finder, and then vector a rescue helicopter to the scene, where survivors were rescued. Without the ELT, they probably would have died of exposure or from their injuries.