A MEEN Stack developer is an asset due to their proficiency in MongoDB, Express.js, Ember.js, and Node.js. This knowledge allows for full-stack development, meaning they can handle both front and back-end development. They can build fast, scalable, and efficient web applications. Their skills in JavaScript-based technologies offer seamless integration and a unified programming language for your project, leading to increased efficiency and easier maintainability. This broad competency makes them an ideal choice for developing complex, high-performance web applications.