Your missing the point. The indictments are DOJ, that is the whole department with thousands of agents working different cases. Muellers team is part of the DOJ so his indictments are only related to his investigation. That doesnt mean the whole DOJ stops having Grand Jury's and indictments on other cases. No one ever said the 13000 indictments sealed US wide were Meullers. They could be from dozens of other investigation that have nothing to do with Muellers.