I'll die on the hill that Helm charts are more of a problem because text/templating is a weird looking templating language then anything else.
I wouldn't say text/template is terribly weird per se, and it's quite reminiscent of Jinja. But what is awful is using a text templating language to generate yaml with the correct level of indentation, and that's where 75% of Helm's problems lie; the other 25% is putting too much logic in templates while working with the clumsy workarounds to text/template having no capability of defining custom functions.
Or to be more specific, issue isn't text/templating as such. It is a fine templating language for text.
But to use a text templating language to generate YAML, which is not only structured, making it a bad match for character based templating with no knowledge of syntax, but indentation-based, making the combination almost seem like a joke.
Helm charts must be the worst engineering solution I have seen in popular use. First time I saw it I didn't believe it, that this was something people did, for real.