Yes, I've looked at it. You need to understand that dmd is still a fledgling project. Note the version number before you trash a software project. It lacks the features of the popular init systems, but it works well enough to run some basic services on the demo Guix VM images.

I love the fact that the configuration is written in Guile. Data is code and code is data after all. I think you're exaggerating the maintenance nightmare. In fact, the Guix project has already proven that newcomers who don't really know s-expression style syntax can write software packages.

Data-based formats are most useful when you know all the requirements one will need up-front, because they need to be coded into your "schema" or DSL - these schemas quickly break down when you have new requirements - and initialization is an extremely diverse area.

The only way to actually manage such a DSL/Schema is to provide a way to "break out" of it into a general purpose language - that's what systemd does by allowing you to run shell scripts in the case you're not using a "standard" service, and it's also what the Nix expression language does in order to build software.

It's far easier to just provide a fully capable language up front - and abstract the common patterns into functions or macros to simplify the usage for users. sysv has worked well with just shell scripts for years, despite it being a sub-standard general purpose language - although various hacks like the LSB init headers have been added to provide some kind of structure to them - a problem that will be better solved with records in Guile.

As for maintenance, I see it as a big plus - with a language like Guile you have access to a useful REPL and debugger - no need to roll your own debugging interface or inspect log files. On top of that, having a dynamic language makes it easier to develop and test patches for new requirements - you're not forced to recompile and restart your DSL.