This is like the paper map vs GPS argument. Which isn't really an argument, as they both do different - if overlapping - things, and have different failure modes that make them useful companions to each other.
Smart things, bank cards and cash can all be used to pay for things, unless you've left them at home, or the shop isn't able to deal with the one you want to use. None are intrinsically better in that respect. Phones can be located when you lose them, or bricked remotely when stolen, and do a zillion unrelated things. Credit cards can open doors and make fraud Somebody Else's Problem. Cash can provide anonymity, hide things from the taxman, work without electricity or boot a tyre. All these things are useful.