To supersede the permission of Sentence 3.4.3.2.(4) not to cumulate exit widths for superimposed floor areas on the basis that all floor areas in an interconnected floor space are subject to exposure from the same fire or other untenable conditions and thus require simultaneous exiting from all floors.
This is to limit the probability that exits will be of insufficient width to permit efficient egress simultaneously from all portions of the interconnected floor space in an emergency situation, which could lead to delays in the evacuation or movement of persons to a safe place, which could lead to harm to persons.