This seems to be 'why': Will I still be able to share photos directly from my Dropbox account to Facebook or Twitter? After July 17, you’ll no longer be able to

This seems to be 'why': Will I still be able to share photos directly from my Dropbox account to Facebook or Twitter? After July 17, you’ll no longer be able to share photos directly from your Dropbox account to social media. You can use shared links to share files or folders on social media.