I don't understand the motivation for any of these "alternative" markup formats. Normal non-technical people want Word (or at least, some kind of WYSIWYG text entry). I've been on projects where they tried to get non-developers to use ReST and it was an abject disaster. The tech writers revolted and refused to use it. So then a developer had to be sidelined to convert their Word documents to ReST so that we could produce HTML.
Yeah HTML is not perfect, but neither is any of these other markup languages. If you like one, fine, but don't wonder why none of them has really caught on outside of small niches of highly technical people.