ADMIN and KHUB_ADMIN users can index metadata in order to make it searchable. In other words, users can enter a metadata value in the search box and instantly find matching content. This can be useful if a metadata key has numerous values, thereby making it difficult to use facets to filter search results.
For example, if a company has one hundred product references which are not part of the content but only specified as metadata keys, users would select a product reference and then have to sort through hundreds of results.