Plus your backup probably requires dozens of CDs and DVDs, and perhaps they then fit on a handful of 4TB drives, and perhaps now they fit on a single 20TB drive

Plus your backup probably requires dozens of CDs and DVDs, and perhaps they then fit on a handful of 4TB drives, and perhaps now they fit on a single 20TB drive. For me, my storage needs increase more or less linearly, but storage capacity increases exponentially, making every cycle easier, involving less drives.