CIA is a surveillance organization with no significant restrictions on what they do outside the US, including on US citizens. FBI is an internal law enforcement

CIA is a surveillance organization with no significant restrictions on what they do outside the US, including on US citizens. FBI is an internal law enforcement agency (ostensibly) limited by american civil protections and due process. If you take the organizations at face value by stated mission, it makes sense that the CIA would have a tremendous amount of information on US citizens that would be proscribed for the FBI. Allowing shared access is just asking for parallel construction and secret courts and shit.