I'm a k8s practitioner and I don't think they were wrong. There are some limitations around maximum number of nodes in a cluster, multi-region clusters, and multi-tenancy that make it difficult for a platform provider intending to serve a global user base that can potentially get very, very big. The simplest solution is to deploy many clusters, but if the solution they went with made it possible to deploy a single control plane, that is a simpler setup and I can't see any good reason not to go with that. At least one advantage of Kubernetes is it already exists, so you don't need to implement a whole bunch of orchestration and separation logic from scratch, but if you're a platform provider, you should have all the expertise to roll your own if pre-existing solutions don't meet your needs. I'd rather do that than tailor my product to the limitations of a toolchain I didn't create myself.