It's not, I need the human readable source part, so I can track my work and cooperate in git :) I use LibreOffice for some stuff though.

Versioning of OpenOffice/LibreOffice documents using git: http://blog.riemann.cc/2013/04/23/versioning-of-openoffice-l...

That is really cool, thanks for that.

Aren't modern word processor formats just zipped-up XML files? I suspect it should be a straight-forward matter to get at least LibreOffice and version control cooperating.

You are technically correct, but not usefully so. The XML is pretty hairy. A VCS that handles XML semantically (e.g. tag-pair oriented, rather than line-oriented) might have some shot....but, basically, merges are more or less not going to work so it's not really version control, just backups.

If we're talking about LaTeX, Word, Markdown and LibreOffice - well, then LibreOffice is a contender for the worst usability, it's superficially similar to a mature product but it's a case of "the remaining 10% of goodness will take more work than the first 90%".

Usability depends on who is using it. I refuse to use LibreOffice because it is so bad, but I would sooner recommend LibreOffice to my father than LaTeX or Markdown.