An auditor asks you to show that customer 1187 was screened against a sanctions list on March 3. The screening job writes a row when it finds a match, and customer 1187 has no rows. That fits two histories: the job ran and found nothing, or the job never ran. The database can’t tell them apart, so you hold no evidence either way.

This is the closed-world assumption doing what SQL has always done: a row that doesn’t exist is false. RDF and OWL went the other way with an open-world assumption, where a missing statement means unknown. Neither has a place for the sentence you actually want to store: I looked here, in this way, at this time, and found nothing.