I don’t know if things have changed but when I started developing apps about 3 years ago, none of the docs or tutorials mentioned persistent storage until the very end, and it would touch on it very lightly.

So when you have developers learning about app dev assuming they will have an internet connection, and most of the time really fast since it’s their dev machine the apps are being built on. Caching sort of becomes and after thought and doesn’t get much attention.

Also, I do recall the api for doing this sort of stuff was very SQL like, at least in the iphone. This probably adds another layer to most devs knowing frontend only and being exposed to CRUD apis.