Kubernetes is a decent example of vendor-supplied and/or mainstream community effort, but that's beside the point that (a) Kubernetes is the exception, not the rule, and (b) Helm is popular for other reasons that belie non-string wire options, like: value overlays (how would you overlay binary-serialized CBOR again?), type safety for the stringly-typed JSON/YAML passed over the wire powered by validating admission webhooks, remote-executed-on-the-cluster hooks for pre-/post- installs/upgrades/uninstalls (big help for database migrations, for example, which cannot be connected to from the machine running Helm), etc.