The primary advantage of using cross-platform development frameworks is their ability to streamline the app development process by allowing developers to write code once and deploy it across multiple platforms, such as iOS and Android. This not only saves time but also reduces costs associated with maintaining separate codebases for each platform. Additionally, these frameworks often come with built-in features that enhance functionality and provide a cohesive user experience. By enabling more efficient development cycles and simplifying updates, cross-platform frameworks can help businesses rapidly respond to market changes and customer needs.