Huh. That was the only reason I used it. What has the most space now, Amazon Drive?
Syncthing doesn't quite have the "Just Works" factor that Dropbox's offering has, but I don't need that; the ability to synchronize several terrabytes of my personal archives (I have a lot of data) was more than worth the effort.
Take this anecdotal report with a dash of salt. It didn't happen to me. Happened to a friend of mine. That said, I wouldn't make Google Drive or Dropbox your only backup either.