Years ago, I came off a horse who had stumbled into a bog, As the horse thrashed to get free it stepped on my chest breaking two ribs. I had to get back on the horse ( wet and covered in mud) and ride two hours back to my truck and then I had a two drive home before I could go see a doc. It was an absolutely miserable experience. Even if I had been able to use a cell phone and call for help. I'll bet rescue workers would have taken at least as long if not longer to find and retrieve me. Sometimes you just have to cowboy up and take care of your self.
This summer we had a fellow come from Austrialia to hike the Highline trail across the Uintas Wilderness. BearKiller knows the area also. He carried both a PLB and a Cell phone. He got lost and was never located. Search and rescue looked for him for more than 3 weeks and never found him. So carrying these devices doesnt guarantee that you will be found or rescued. They suspect, what ever got him, happened so fast, he had no chance to use the devices. A snow cornice colapse burried him under snow. Crossing a fast moving river and loose your footing and drown. It may be years before somebody stumbles across his remains and determine what happened to him.
Sometimes when accidents happen, You don't have the time or ability to use these high tech devices. A good friend of mine went for a ride on a sunny February afternoon. His horse slipped in some mud, My friend broke his pelvis and ruptured his bladder as he slammed into the saddle horn as the horse went down. Once on the ground, he was never able to get back to his feet. Even though his horse stayed with him. His cell phone didn't work, because he was behind a ridge that shielded him from the tower. About 9pm that night his wife got worried and called the sheriff who came looking for him. They flew by him with a helocopter several times, but never spoted him or his horse. Finally 14 hours after he got hurt, Searchers on ATV's found him laying ont he trail in 16° temps. It took another two hours to get him into a life flight helocopter and rescued to a hospital.
Point is we have chosen a hobby that has the possibility of getting hurt. Each rider will need to access the area he rides and choose for himself the risk that he is willing to accept. Having these devices is better than not having them, But often times having others with you is a much better option. I do ride alone, probably shouldn't, But it is a risk I take and I at least let my wife know where I'm going and when to expect me home.
Some of the placs I ride are 40 miles from the nearest town, Cell signals don't work in a lot of places.
GPS and SPOT signals will probably reach down into the canyons, But cell signals will never reach into places like this.