I do thank the advent of LLM's for making the task of tracing through 3 layers of YAML rendering indirection to find an actual bug in layers of insanity. They are surprisingly good at it. A purist might look at the system and be taken aback in horror, but pragmatically the crazy templating things that used to be pretty major in terms of maintainability have become a lot less problematic.

I don't even mind text interpolation in helm that much. Yes, it's horrific, but it really doesn't become problematic until you are having an external system render the text being sent to helm that might be processed again after the fact with Kustomize. Your text might hit literally 3-4 different YAML rendering pipelines before it finally hits your cluster. Insanity

Hashicorp had a similar idea to this configuration language you are mentioning. They named it HCL. We do know how that turned out, but maybe that was more questionable design rather than problems endemic to the approach.

It's why, except for upstream charts, I use exclusively jsonnet (through kubecfg) when I can.

String interpolation is a pox on the ecosystem, especially given how YAML was only originally a debug helper...