I can think of a number of routes to rarity.

1. Object was very expensive when made, so not many were made in the first place.
2. Object was undesirable when made, so not many sold.
3. Object was widely made, but of poor quality or durability, so most ended up in the trash (e.g. chipboard wardrobe or ancient pottery).
4. Object was widely made but of low perceived value, so most were discarded as worthless (e.g. disposable phone cards).
5. Object rapidly superceded by something better (i.e. most old bits of technology)
6. Object actively destroyed or defaced by a culture that declares it's symbology offensive.
7. Object worth more for scrap.

There's very little in the list to do with quality.