You could also use docbook. My gut feeling is, that if you have large documents that you collaboratively work on, there's probably a bit of a compilation proces

You could also use docbook. My gut feeling is, that if you have large documents that you collaboratively work on, there's probably a bit of a compilation process to be done and other stuff you want to do with the document. So the overhead of semantic markup of the whole content (instead of just marking words as bold) might be worth it.