If I think about a document web, I don't think everyone will like to write in Markdown. There are many ''lightweight markup language''s to choose from. So maybe there could be a ''low-level'' markup language like Scribe or Texinfo to compile into from your favourite markup language. I have a small example of what that might look like here (just the sketch, not impl): https://news.ycombinator.com/item?id=24249636
What do you think?