I’m actually working on a new markup language (similar to markdown) using as much free time as possible. Finally after five years I’ll be Markdown-free and org-mode-free.
Being able to have full control of the concrete syntax is surprisingly important when dealing with DSLs that for some reason do have a concrete syntax. Like, sometimes people base their DSL on stuff like YAML, which basically means you have to say goodbye to source-level transformations that preserve comments (because almost no existing libraries expose such an AST. You want to write one yourself? Good luck parsing that pile of dog shit my friend). JSON is a different story because people just do
"comment": "put your comment here" (which will obviously be preserved). Even if without this kind of far-stretching reasons, being independent is still a much more favorable state, especially after all these years knowing how many things you normally depend on could be fucked up big time.