Life Safety is obviously the first priority in any fire situation. An orderly evacuation reduces the risk of loss of life or injury. Rated fire doors are just that, rated to provide protection from thermal/fire spread in accordance with their respective fire rating. Humans however are more likely killed or injured from smoke inhalation/toxic fumes/oxygen displacement, then being burned alive. Fire rated doors will provide some thermal protection and reduce the spread of fire, but depending upon the condition of the door seals/gaskets, may provide significantly less protection from those things (smoke inhalation/toxic fumes/oxygen displacement) that will likely kill you.

Most large structures with high occupancy risks are made from concrete, cinder block, brick, etc. The structure itself will likely not burn, but all of the wiring, carpets, furniture, paper, drapes, all pose significant smoke/toxic gas treats. Doors that are opened do increase the chance of fire/smoke spread, mainly if multiple doors are opened at the same time (think of cross ventilation). However, limiting the amount of oxygen available to a fire, will generally in and of itself not extinguish the fire. In fact the reduced heat will likely produce greater amounts of smoke/toxic gases, as incomplete combustion is more likely.

My personal belief is an orderly evacuation should remain the top priority; once you are out, you no longer present yourself as a potential victim requiring rescue.

Pete