The step that collects facts has no AI in it
Every other stage uses a model. This one deliberately does not. A model sitting between the search results and the record of facts could summarise, smooth over, or quietly drop a detail, and every check after that would be measuring the article against a record that was already wrong.
Translation never touches the evidence
When the sources are in a different language from the one you asked in, verification still compares the finished article against the originals rather than the translated version. A slip in translation cannot disguise an invented fact, and it cannot be mistaken for one either.
Publishing nothing is a valid outcome
Most systems treat a failed check as an obstacle to route around. Here it is the product working as designed. A run that stops and tells you exactly which claims it could not stand behind is worth more than one that prints them quietly and leaves you to find out later.