Using a proper programming language seems to be the obvious end-game of configuration. Everything as code. Not quite sure why we keep trying and failing to use non-Turing complete configuration languages.
The worst offense is perhaps that we've evolved quite intuitive languages that would impeccably serve most con/prosumer needs as far as "mostly static but smartly architected" configurations are concerned.
Python, Go, even Scratch (for a 100% GUX)… And among the many pros, error handling is enough to warrant the change from markup.
But IMHO here's the one barrier: people need to stop thinking of an Information System (IS) as a collection of machines, and move one level of abstraction above to consider said IS as the unit, and machines as subs of sort (subsystems, components, modules, call it what you want). Conceptually, your "main" space is the IS, everything else is modules down the namespace hierarchy. We need to think of machines as we used to think of programs, and think of IS's as we used to think of machines. In the UNIX philosophy, any application is a collection of programs, just as an IS-as-code is a collection of machines-as-software-modules (basically feature libraries for "main" to use).
When that paradigm comes, you'll be able to simply "import" some subsystem (say Elastic Search, whatever machines in the IS) and add that (as a class, method, whatever) to all your existing objects, because the concept of "interfaces" (quite literally the basis of interoperability, dating back forever in computing) will be _native_ to your IS model in a Turing-complete paradigm.
Not sure my wording made sense to non-programmers (cue: "quotes" are technical terms, not general meaning), but I'm too lazy to write a layman expose.
The issue isn't that they're Turing complete or not, but that people are hacking programming language features on top of YAML in the worst conceivable way. Like if you were regular sadistic, you would say "I'm not going to write Python, I'm going to write Python's AST in YAML", but if you're advanced sadistic you say "I'm not going to write Python's AST in YAML, I'm going to make up an AST for a programming language that doesn't exist with bizarre and inconsistent semantics in YAML (YAML has lists, but I'm going to make people pass lists as comma-delineated strings--it'll be a riot)".
