MongoDB has become the most popular non-relational database due to its ability to facilitate iteration and adaptation, which is critical for satisfying customers and staying competitive in today's fast-paced market. The document-oriented data model of MongoDB makes it exceptionally easy to add or change fields, allowing developers to quickly evolve applications without having to fit them into a predefined schema. This flexibility enables profound developer agility, making MongoDB an ideal choice for companies that need to continuously iterate on their applications and adapt to changing user needs.