Markup. Comes in many flavours.
Great because it is basically plain-text. Doesn’t require any special tools for editing.
It does to some extent require you to be familiar with HTML and how websites are structured. It is a steep learning curce for someone who’s used to editing linear documents in Word.
Missing some key features like blocks, built-in support for transclusion, metadata.
Content blocks in markdown
I’m not sure what I think of this yet (maybe cluttering an already fragile format), but the incentive here is similar to some ideas in Hypermedia document editing environment.
I think the markdown becomes messy, and it starts to loose its human-readable nature.
I reckon a more loosely coupled approach where things are connected using Semantic triples (RDF triples) would be more favourable.