So you never see conflict messages or conflicted files in your Dropbox? In the few cases I've tried a git working copy on Dropbox -- which is what I believe the author is discussing -- I've had conflicts.
For example:
$ ls -1 .git/index*
index
index (blacktip.esquimaux.org's conflicted copy 2013-04-09)
index (hammerhead's conflicted copy 2012-01-30)
index (holodeck's conflicted copy 2012-01-26 (1))
index (holodeck's conflicted copy 2012-01-26)
index (holodeck's conflicted copy 2013-04-09)
It was only the index file and not anything irreplaceable (not that git does a lot of mutating of files in general). But it rapidly ended my experiment with git on Dropbox.