Many projects don't even need cluster state, they could have just used a Makefile and some sed templating [0] (get off my lawn). Thankfully in these cases you can use helm offline to render the templates then just apply them but it's not great.
Thus I'm sour on Helm, I'm rooting for Kustomize. [1]
[0] https://github.com/kubernetes/kubernetes/blob/master/cluster...