The Ember CLI is like a dependency packager, test runner, optimizer, and local server—all rolled into one. Since all features were built to work together, common tasks (e.g. upgrading the app version and deploying the app) can be automated with production-ready, open source plugins. The CLI is backwards-compatible with older Ember apps and maintains a 6-week release schedule.
The CLI was also built with the idea that a developer should be able to focus on building great apps, not re-engineering how to fit pieces together throughout an app's lifecycle. Apps become maintainable and approachable, since there are established architectural patterns across individuals, teams, and companies. However, if you want to make your own adjustments, such as using a different testing library, you still can.
