It's easy to lose the trail in some terrain and the people you're talking about likely wouldn't know what to do about it. Just last week I saved one of those guys from at best a rather unpleasant experience, at worst being stranded in the wilderness--and he didn't even lose the trail.
We had met on a local summit although we had approached it via different routes. We were on a spur off a longer trail--and he took the wrong direction when coming back to the main trail. I encountered him probably an hour later and realized his mistake and got him headed back to his car. Had he continued there was one junction ahead--if he took the left branch he would end up where I was parked which was miles from his car. If he took the right branch he would have failed to end up at a slightly more distant parking lot as by the trail it was about 16 miles away, going over a summit just below 12k' (we were a bit above 9k' at the time) in the process. His phone battery was dead, it was near the new moon and that route goes near cliffs.