The article assumes there are people who want clusters. But a single Linux VM in the cloud can scale pretty far. Separate VM's for different apps works well for isolation. Why do I need a cluster?

Wouldn’t it be cheaper / less complex to scale vertically (eg a large workstation or medium size bare metal server) instead of using clusters? My understanding is that clusters are primarily useful when you want to share a resource from a pool across unpredictable usage, which becomes a moot point once the cluster is personal.

I have an irrational soft spot for Apache Mesos. I loved the separation of the resource management from the scheduling. Note to self: do not rabbit hole on this. Hm. Maybe mesos is the manager for my agent sandboxes. No! Bad lowbloodsugar!

I’m not sure quite what this is trying to say. My laptop is already a personal cluster — it has 16 cores, lots of storage, a fast network, I run VMs on it. It’s been the case for a long time that you can run bursty jobs in the cloud if you need more power for a brief period than whatever is currently locally affordable. That’s kind of what the cloud is for, really. So what’s new?

No idea about ClusterOS, but I would recommend IncusOS if you're looking for a nice clustering solution. Incus has become indispensable in my homelab over the past few months. It's what I put on my bare metal machines and then spin up Talos Linux VMs for day job practice.