I know kubeflow can use namespaces for its own purposes, but otherwise I thought that was quite rare. Namespaces are intended to be used for exactly this usecase (isolating teams and/or workloads).

What kind of system have you seen where this isn't true?

We've seen plenty of examples where people do this. Sometimes it's different teams (e.g. the ML team is namespaced away from the primary customer flow) and sometimes it's for different customers. Really, it sounds like we're in agreement about why this happens, the confusion is just whether or not that normally happens within a company in the course of doing business?

Gotcha. If you're looking for subnamespacing, HNC offers self-service subnamespace creation, have you looked into that? https://github.com/kubernetes-sigs/multi-tenancy/tree/master...

(My apologies if we've chatted about this before in another venue, I'm losing track of whom I've already talked to)

I use namespaces to isolate names. So I can have a service called memcached in namespace A and also one in namespace B.