Ephemeral user accounts were agreed upon before that. The OG container
Docker and k8s are just wrappers around namespaces, cgroups, file system ACLs, some essential cli commands, which can also be configured per user.
We may be headed back there. Have seen some experiments leveraging Linux kernels BPF and sched_ext to fire off just the right sized compute schedule in response to sequences of specific BPF events.
Future "containers" may just be kernel processes and threads... again. Especially if enough human agency looks away from software as AI makes employment for enough people untenable. Why would those who remain want to manage kernels and k8s complexity?
Imo its less we agreed on k8s specifically and more we agreed to let people use all the free money to develop whatever was believed to make the job easier; but if the jobs go away then it's just more work for the few left