Would be relevant for folks like Backblaze and the Internet Archive, where you write once, read many, but rarely delete. 60 72TB drives gets you 4.3PB per chassis/pod, and assuming 10 pods to a rack, 40PB racks. For comparison, 3 years ago, the Internet Archive had about 50PB of data archived and 120PB of raw disk capacity.
And as "rarely" approaches zero ( think legal hold-type "you may surely not delete" ) there is a cost-saving in warm-ish storage in terms of replication and maintenance. Ensuring that your Tape archive is good is a pain unless you have huge tape robots - https://www.youtube.com/watch?v=kiNWOhl00Ao
https://news.ycombinator.com/item?id=18118556