That is to say, if Tarsnap is the only place you've keeping sensitive/important data, then you're "not doing it right" as a backup. Things happen... your hard drive can die suddenly, and a data center bursts into flames all on the same day.
To be fair, they deserve it a bit as they got up in flames twice .
Indeed, after the first fire, the geniuses over there collected all the UPS and batteries they could find from the DC and stored them all in a pile in a closed container... where they predictably bulged, failed, sparked and eventually triggered another fire after a couple days.