For apps that read a lot more than they write, there exist ACID databases in which reads don't have to touch network, while retaining consistent writes. Datomic is one; for those who have never studied datomic, the database storage is immutable in the same way that Git commits are immutable, which enables a lot of git-like things in your database, like queries without network. That way your apps can be fast without giving up ACID.

I don't know if anything like Datomic exists on mobile; and OP is talking about mobile apps not webapps; so OP may be kind of correct, at least today.