I didn't downvote you, but I don't really agree this is not an issue. The article itself shows that the git repo can get into a confused state which you have to fix, even if the fix is simple. The experiment itself doesn't emulate common causes of Dropbox pain. Firstly Dropbox stores and syncs files in a way that gits number of files and layout of files is not kind to, causing thrashing and high cpu when people commit. Different clients have different ways of locking a git repo. Issues occur when two clients make changes and are online at different times. I'm not saying everyone will hit these issues, but these are all issues that someone has run into.
Edit: Wow I got downvoted and I actually ran the experiments myself. Has anyone got experiments showing otherwise?