How so? I find it much the same to other templating engines like Jinja, though I'm definitely not a fan of the syntax. But that hardly matters anymore with LLMs.
Specifically with YAML, Go templating requires some special operators to get anything useful done and it ends up being an unreadable mess.
I think it's a combination of text templating + yaml (which is whitespace delimited). When templating html with Jinja, it's not a big deal if the indentation isn't right. In helm, best case you get a syntax error, worst case you end up overwriting keys and producing something syntactically but not logically correct.