A lot of things can break (hardware, networking, ...). Spanning the workload over multiple clusters in different regions is already satisfying the "backup clust

A lot of things can break (hardware, networking, ...). Spanning the workload over multiple clusters in different regions is already satisfying the "backup cluster" recommendation. Many workloads don't need to be multi-region as a requirement. So they might run just on one cluster with the option to fail over to another region in case of an emergency. Running a workload on one cluster at a time (even with some downtime for a manual failover) makes a lot of things much easier. Many workloads don't need 99,99% availability, and nothing awful happens if they are down for a few hours.