Earlier quoted context omitted.
> Todo app 15 years ago was a simple CRUD app. Today todo app has to do CRUD, sync, offline mode, public API, integrations with popular services, collaborative projects and support 6 platforms. Sync was done in many ways, thanks to the app using actual files to store information. It wasn't a concern of the app itself - nor it should be. Off-line mode was the default. Public API wasn't needed. Collaborative projects i…
"Feature" phones from 20 years ago (most Nokia and Ericsson even into the android era) could sync personal data such as phone book and calendar over the internet [0]. The libraries doing this were originally written in C and their compiled versions took up maybe tens of kb running on constrained hardware. The functionality is not remarkable. The UX of those phones was pretty poor though. [0] - SyncML.
> The UX of those phones was pretty poor though.
That... really depends. Having physical buttons was nice. I could write on those numeric keypads about as fast as I do on full touchscreen keyboard today, except I'd make less errors and could do it without looking at my fingers.
Which brings me to one piece of feature phone UX I strongly miss to this day: fixed latency. The firmware/OS was pretty much (or maybe even de facto) a real-time OS. With few rare exceptions, every interaction had consistent, fixed latency. Because of that (and physical buttons), I quickly learned to operate my phone without looking at it, or even pulling it out of my pocket. Unlock, menu, down, down, OK, [wait 1 second], down, OK, start typing... - these kind of sequences quickly became muscle memory.
All that was lost with switch to smartphones, as both Android and iOS have randomly changing and unpredictable UI latency, and the UI itself isn't fixed in space either.