The primary benefit of a microservices architecture in software development is its ability to enhance modularity and scalability. This architectural style divides an application into smaller, loosely coupled services that can be developed, deployed, and maintained independently. This allows teams to innovate and iterate rapidly, making it easier to implement updates and new features without disrupting the entire application. Additionally, microservices facilitate the use of diverse technologies and improve fault tolerance, as issues in one service do not directly impact others. Ultimately, this approach leads to greater efficiency and agility in software development.