People forget that the "rule of least power" is "the language with the least power suitable for the task". The question is whether YAML/HCL are suitable for the task to begin with. The following facts all testify that it is not, and that the principle of least power favors "real programming languages":

* CloudFormation hacks things like references, nested-stacks, macros, imports, etc onto YAML

* HCL becomes more powerful with each version

* Helm generates YAML with templates and recently added support for Lua

* AWS is building its CDK, which generates CloudFormation with programming languages

* Things like Terraform and Pulumi exist