I believe a "small" misunderstanding has developed here.
The original text refers to the US definition of flight dispatch which I belive it's called Ops controller in the UK.
Nothing to do with loading aircraft or checking passports.
And yes, in the US the Flight Dispatcher/Operations Controller does share a 50% responsability with the Captain, before and during the flight.
"In cooperation with the pilot, the flight dispatcher furnishes a flight plan that enables the aircraft to arrive at its destination on schedule with the maximum payload and the least operating cost. The flight dispatcher considers en route and destination weather, winds aloft, alternate destinations, fuel required, altitudes, and traffic flow. The dispatcher's signature, along with that of the pilot, releases the aircraft for flight. The dispatcher maintains a constant watch on all flights dispatched, and is responsible in joint agreement with the airline captain for flight planning, route and altitude selection, fuel load requirements, aircraft legality and complyig with FAA regulations. The dispatcher is the go-between for the pilot and ground service personnel, and keeps all personnel concerned with the flight informed about its status. The dispatcher must be familiar with navigation facilities over airline routes and at airports as well as with the takeoff, cruising, and landing characteristics of all aircraft operated by the airline. The flight dispatcher also must ride periodically in the cockpit with the flight crew to observe flight routes, conditions, and airports."