If you're going distributed the first place, doesn't that often imply that big team / big codebase?

In those cases, I'd argue things will likely come up quite quickly. Kubernetes is key component of a platform, but not a PaaS, e.g. you are required to understand to low level stuff, even if it's managed by a public cloud provider.

Cue out of memory apps, recovering GB+ JVM thread dumps out of a transient container, lack of troubleshooting tools, the kinda of stuff falcolas said above, plus high pressure to resolve because it's highly visible production app and you're got a recipe for sadness.

Even at google AFAIK, K8S ran in the context of BORG/ BORGMON and a host of other internal tools.