The problem is that we sometimes need smartphones for looking things up. Like looking up whether some shop is open, or when the next train will go. Sure, we could live without them, like we did 20 years ago, but it wasn't easy. :(
I guess I'm lucky -- I almost never use my phone to look things up like that.
I will be switching to a dumbphone when my current smartphone dies, because keeping the smartphone secure has become unmanageably difficult to do and with every release, gets more so.
But I will be carrying a pocket computer as well as the dumb phone. That's what I really wanted my smartphone to be -- a computer I always have with me -- anyway, and smartphones were never very good at being that.
So, by tethering the pocket computer to the dumbphone, I can look things up when I need anyway.