These are valid use cases for multiple clusters in a workload domain according to VMware documentation. A workload domain with multiple availability zones each containing clusters can provide high availability and disaster recovery by distributing workloads across different physical locations within a region. A workload domain with multiple clusters in one rack can provide scalability and flexibility by allowing different configurations and policies for different clusters within a single logical unit. Two clusters forming one stretched workload domain can provide resiliency and fault tolerance by synchronizing data across two sites within a region.