I think the big problem is on most "dumb-ish" phones the SMS app can't access critical information of the phone like location. So let's say I wanted to just text an uber to pick me up and drop me off, I now need to go into a location app to get the address or coordinates, so I might as well just use the uber app directly that combines address lookup with ordering the ride.
Probably many other examples where you can't get the exact info you need in order to communicate to a system over SMS without another app providing it.
I think the big problem is on most "dumb-ish" phones the SMS app can't access critical information of the phone like location. So let's say I wanted to just text an uber to pick me up and drop me off, I now need to go into a location app to get the address or coordinates, so I might as well just use the uber app directly that combines address lookup with ordering the ride.
Probably many other examples where you can't get the exact info you need in order to communicate to a system over SMS without another app providing it.