This is needed if we want to switch the SqlEntitiesWithoutTermFinder implementation to not make use of the wb_entity_per_page table. Changing the implementation to join against the page table by using a str replace on the entity id is less efficient, so we need to be sure we can restrict that in production to properties (where we only have a few thousand rows).

In T140891#2479890, @Lydia_Pintscher wrote:

I just discussed with Daniel if we actually need Special:EntitiesWithoutDescription and Special:EntitiesWithoutLabel They lost their usefulness mostly as Wikidata grew. If you want to find items without a label in a given language the resultset is in most cases too large to be useful. A tool like https://tools.wmflabs.org/wikidata-terminator/ is needed to help find the items where a label or description is actually important to have.
The one remaining usecase for the special pages is then doing this for properties. Here the number is manageable and useful. So we can optimize for this case and remove the item case.

In T140891#2479927, @daniel wrote:

The idea behind restricting to Properties is: Without wb_entity_per_page, joining against the wb_terms table is inefficient. It would still work for Properties though, because there aren't that many of them.