That's the thing. There's nothing really "custom" here. The files themselves are all still standard markdown with yaml frontmatter. The only difference is that

That's the thing. There's nothing really "custom" here. The files themselves are all still standard markdown with yaml frontmatter. The only difference is that there's now a nice, performant interface for getting an overview for all those files - something that you could fairly trivially make with a script, if you really needed to recreate it. And the file specifying what your views were is, itself, plaintext. There's no lock-in here, and the spec is open and well-documented.