I'd argue that using helm charts is the exact opposite of NIH. The things that take time are not the stack themselves, but the software and solutions. K8s just makes the stack defined in code, and written and managed by dedicated people (helm maintainers) as opposed to a bit "all over the place" and otherwise in-house, directly using cloud provider lock-in resources.

I'm sure there are plenty of use cases where that makes sense, and is a better approach. But, I disagree that k8s suggests a NIH-mindset.