Right, but it lets you/your personal connection avoid one leg:
instead of torrent -> local dropbox -> cloud dropbox,
you get only use your bandwidth for cloud dropbox -> local dropbox.
Given that many residential ISPs that meter data service don't differentiate between uploaded vs. downloaded data, that's a potentially valuable way to externalize the bandwidth requirements for your torrent (of undoubtedly legal/paid or public domain content, I'm sure)...