What is the benefit of a request mocking framework versus hiding all api requests behind a module?

Instead of

    // MyComponent.js
    const users = await fetch(...

Use this

    // MyComponent.js
    const users = await api.getUsers()

    // api.js
    export default {
      getUsers() {
        return fetch(...
      }
    }

To mock, you replace the entire api module (or individual functions).