Cloud Run (and Cloud Run for Anthos) is a container-based serverless technology. A distinct advantage here is that containerization is a widely adopted approach. Being able to package your application as a container and then subsequently migrate it to a fully managed serverless environment without any additional work is a desirable proposition.
When working with any technology, it is always good to have an understanding of the constituent parts. In this respect, Google Cloud has chosen to base its technology on several open source technologies that the community can contribute to. Underestimating the ability to move between cloud providers occurs frequently. When developing an application, an important consideration is how that product/service technology can be adapted and the support it will receive.
Beyond the fundamental proposition of running containers...