I've personally boiled down the Helm vs. Kubernetes to the following:

Does your Kubernetes configuration need to be installed by a stranger? Use Helm.

Does your Kubernetes configuration need to be installed by you and your organization alone? Use Kustomize.

It makes sense for Grafana to provide a Helm chart for Grafana Alloy that the employees of Random Corp can install on their servers. It doesn't make sense for my employer to make a Helm chart out of our SaaS application just so that we can have different prod/staging settings.