A friend will help you when you are in trouble.
I started down a rocky riverside while hiking in Vermont near Buttermilk Falls. The rocky riverbed was a classic place to snap an ankle, and I had my 1 year old daughter strapped to my back for the hike. My wife was not far away up the river, but wouldn't be able to hear or see me if something went wrong.
In one of the pouches of my backpack I had a device which could send two-way, real-time voice and video to an antenna miles away; a cellphone. It was utterly useless despite there being another just like it being carried by my wife, with exactly the same capabilities, a few hundreds yards away. Both cellphones were showing "no signal", as they typically do in many rural areas.
Both cellphones have the transmission power to reach a cell-tower miles away, yet are designed to ignore one another even if they are placed side-by-side. They are designed to be gateways to the cellphone provider's infrastructure, as opposed to general purpose communication devices with peer-to-peer capabilities.
With a peer-to-peer cellphone I would have been confident that I could call my wife if I got into trouble on my route. With what I actually had on me at the time I could either reach through the cellular provider (and allow them to track where I am, charge me for services, update the firmware of my device, etc.), or nothing at all. Since I couldn't reach the cellular provider, I got nothing. That day I reached the conclusion that cellphones are designed without our best interests in mind.
Since the signal strength weakens on the order of the inverse of the square with respect to distance, a peer-to-peer system would mean less cell-towers in urban areas where you are guaranteed to have many other cellular devices close by. This translates to better battery performance and physically cooler devices (a more powerful transmitter results in more heat waste.) So there are practical reasons to incorporate a peer-to-peer system into the existing design. With a peer to peer system an emergency call could be placed to a nearby cellphone from a cellphone which is out of range. This process could be repeated until a cellphone is found with access to a cell-tower (opportunistically routing through nodes like this is how the entire Internet works.)
In reality there are many problems with the modern cellphone, and this is just one of them. But it points to the underlying with cellphones; they aren't our friends.