Glad to hear I'm not the only one. I appreciate the helm design and I don't dispute people have a fine time using it. I just need something simple to render yaml from a template without regard to cluster state, so we use good old fashioned sed.
What's annoying about helm is many cases would be fine as plain yaml template macro without any cluster state but many public projects are packaged as helm charts so to use them off the shelf you need to go full helm. Thankfully it's not too difficult to use helm template.
Tiller actually doesn't even really look at the current state in the cluster. It basically just hard fails if the resource already exists when it shouldn't, but it doesn't attempt to reconcile manual edits to resources outside of the helm upgrade lifecycle.
As I understand it the upcoming version of helm ditches tiller completely.