Actually that sounds quaint and how folks used to use cellphones when they cost $1/minute and had 1 hour battery life.
We don't have a landline. Everyone in my family and most of my friends are on the same carrier so we have "free" calling.
I think cellphones have incredible utility value. Just yesterday morning I had a two hour drive to meet someone and about ten minutes into the ride the guy called and said he had a family emergency and needed to reschedule. If my phone was turned off I would have wasted 4 hours of driving. And with a smartphone I can often resolve stuff in minutes. Also I can search stuff, look up prices, get notifications on deliveries and handy stuff like being able to check the weather radar when we are out cycling to decide how long we have until the storm instead of the old days of "rain is forecast , lets ride another day"