And in the 21st Century, everyone rents extra space just to store all of the extra stuff we own but won't ever use again.
;^)
Owners are not avoiding the tasks of sorting through such things, they're avoiding the emotions attached to the tasks.
We're missing formal or semi-formal rituals of selling, donating, discarding, or destroying items. Our ancestors never created such rituals because they never owned enough stuff to begin with.
Also, many of those items are obsolete but not replaced. VHS cassettes are a good example. The cost of replacing a VHS library with DVDs isn't worth it, and not every VHS is available on DVD, download, or streaming. Instead of becoming an video archive expert, one simply boxes them all away. The same is true of CDs and audio cassettes.