So here's a story: I work at a large engineering company building custom automated research systems. The system engineers do the the design/development/testing and documentation.
I have been searching for nearly 9 months for a documentation system to replace our current documentation system (500 Word docs in an EDMS). Goal is to increase re-usability and decrease maintenance cost by something more like a wiki/markdown system.
The problem is, even though formatting and maintenance of Word docs is abysmal, they make inserting images and references drop dead simple. Plus, everyone has it installed on their machine.
All the markdown versions don't have good references or image support (plus the best IDE is gitbooks which is... buggy). RsT is too much of a burden to setup. These are engineers writing, not programmers.
I've looked into Confluence, Gitbooks, Dozuki, Inkling, Sphinx, ... nothing is quite so friction-less to "just write the docs" than Word.