Almost all scientific papers have more than one author, so collaboration and version control features are also important, but were not considered in this study. (For example, since .tex files are plain text they can be conveniently managed with git)
Also, if the intent is to determine which system should be used to "save time and money", the cost of licensing proprietary software must also be considered.
Although I mainly use LaTeX and prefer its semantic markup, the revision control is one thing I do prefer about Word, at least for my workflow. There are cases where I could imagine the git tooling/workflow being superior, but for me personally it hasn't worked well. Whereas Word's "track changes" mode works well for me as a way of suggesting, commenting on, and integrating revisions (replacing a lot of email traffic).
Well, it's not just "git"... it's any of the tools people use to compare and collaborate on text files. Throw it in a Rietveld instance or Gerrit, and you can review changes and make comments like with any other code review. If you prefer just throwing it into kdiff3 or something, you can do that, too. If you like Word's "Track Changes", LyX has that (though that means everyone has to use LyX as their editor).
The point is that a simple text-based source format opens up the possibility for lots of different collaboration models that the Word software monoculture prevents.
Also, if the intent is to determine which system should be used to "save time and money", the cost of licensing proprietary software must also be considered.