My concern with cel phones is like that others who have posted here, I think people will rely on them for rescue, instead of learning how to avoid rescue in the first place.
The problem with that theory is accidents happen to people who are extremely cautious and prepared, even to the point of carrying cell phones.
There will always be the element in society who travel unprepared and who are careless about lots of things in life, yet their cell phones are always "attached at the hip" 24-7. God forbid that they should ever be separated for any reason.
I don't think most give it a second thought that something terrible could happen and they might have to call 911, but rather they cannot bear the thought of missing or making calls to their pals. In fact, I have experienced this first hand while hiking with two friends on two separate occasions. I no longer hike with them. I doubt the battery would have have any life left in it if we did have to call 911.
Would any of us not carry a headlamp because we are absolutely certain that we will not exit the woods after dark. Surprise! We take a wrong turn and are benighted.
The cell phone is not an insurance policy that we will not have an accident anymore than not carrying a headlamp insures that we will be out before sunset, even with the very best of intentions. You could even find yourself with a double whammy, lost or injured with no light and no cell phone to try to call for help.
I would think SAR would rather know sooner than later if someone is lost or injured on the mountain for whatever reason it might have happened. In fact, it might be careless to not carry a CP because their job could be made even more difficult not being able to communicate with you or track you with the "ping". Hopefully, you would have a signal. Those of us who would attempt self-rescue would do it one way or the other, but there will always be those who would not even give it a thought. They would sit on a rock, cry, and hopefully not die.
Accidents happen and if I have one, I think I would rather be able to contact emergency personnel sooner that later. I think they would sooner take a foolish live victim down that someone in a body bag who died because help did not come soon enough. In the Whites, they could always charge you for the rescue if you were not hiking safely.
Just my 2 cents!