>"What are we writing for?"
I'll argue that paper and pencil can be the most helpful first aid / emergency supply. A little less now in an age of cell phone and SPOT devices, but back when messages got relayed by humans, it was amazing how the story could change with just a few people involved. Passing an original note avoid that. A note left at a trail junction sign or on a car can communicate so much better than a arrow created from sticks and rocks.
That said, with a mini-sharpie along, anything is paper (hat, sleeve, rock, skin of your arm, pot lid, smooth stick, underwear waist band, etc.)
For the same reason, I prefer texts for critical communications than rather voice calls. A friend made a lame joke over a bad phone connection just before the connection failed and was surprised when a helicopter showed up 30 minutes later. His supervisor was not amused.