I never used something like OpenSSI, but I'd be surprised if running over (presumably) Ethernet of the time worked well for an SSI compared with the "expensive"

I never used something like OpenSSI, but I'd be surprised if running over (presumably) Ethernet of the time worked well for an SSI compared with the "expensive" things like SGI Origin with fast links and hardware coherence. Solutions like that still exist, and there's the SCI standard. Current things like NVlink and CAPI seem to be rather in the same direction. I don't think Kubernetes is a fundamentally different abstraction to the (HPC) distributed resource managers that ran on shared- and distributed-memory systems of the time. (In that space MPI somewhat standardizes remote memory access and process spawning.)