REST APIs are commonly used for web app development due to their simplicity and widespread support, allowing developers to perform CRUD operations via HTTP requests. However, they present challenges such as a lack of schema validation, data type inconsistencies, and complex data transformations, which can lead to app instability and inefficiency. Additionally, translating complex business logic into REST's simple transport model and dealing with unreliable internet connectivity can further complicate development. Couchbase Mobile addresses these issues by offering a comprehensive platform that eliminates the need for REST by providing an embedded database for offline functionality, automatic data synchronization via websockets, and support for peer-to-peer data sharing, ultimately simplifying development and enhancing app performance and reliability.