Using Ruby on Rails with MongoDB offers significant benefits for scalable web development. This powerful duo enhances both flexibility and performance, making it an ideal choice for developers seeking to build robust applications. Ruby on Rails provides a solid framework that simplifies the development process, while MongoDB, as a NoSQL database, offers the flexibility to handle unstructured data and scale effortlessly. Together, they create a development environment that can adapt to the evolving needs of modern web applications, ensuring high performance and scalability.