Re: What is the point of the IoCCO?
They are tasked with providing the oversight, and doing the investigation. They are the ones who identified the problem in the first case, and then did the deeper dive. They then refer it to the Investigatory Powers Tribunal (and/or tell the affected parties how to do so themselves). The IPT is a court.
Think of IOCCO as the police. They do the investigation, and then pass on the prosecution to the court system.