I would really hope that the presence of a "Backups" checkbox on the droplet creation page is enough to tell the (presumably tech-savvy) user that backups don't happen unless you check that box.
That's fine, but they didn't introduce this functionality until recently. One day, I logged into my DO console (I don't have a reason to do this very often), and saw a new backup tab. Older customers might not even be aware.
I don't host anything I couldn't live without though, so I'm not really worried.
The functionality has been there for a long time. It's possible the checkbox on droplet creation is new, and it used to require activating backups afterwards, I don't recall.
That's probably wise, I really should do the same. My important stuff is in git with a remote repository, but losing all my configuration and setup would still not be great.