The didn't. If you fell down into a crevice, you died. You could apply the same spurious argument to anything - how did people ever get by for thousands of years before antibiotics/vaccines/electricity/water purification existed? They didn't, they lived their nasty, brutish and short lives, and died.

I could argue that cell phones (etc.) are technology that is basically: "Come rescue me." There are plenty of other technologies that we can use to help ourselves (maps, compasses, matches, and so forth). I'm at least somewhat uncomfortable with saying that calling for help is quite in the same category.

There's a simple way to avoid it, with or without cellphones: don't go to dangerous places without being prepared for it.