In a health care occupancy, the occupants are not necessarily able to use exits, regardless of the number of exits provided. Occupants might be immobile, wired to monitoring equipment, debilitated, or recovering from surgery; or they might be disabled in some other way.
The Code, in this instance, calls for a defend-in-place design strategy that uses horizontal movement and compartmentation. It recognizes that the occupants are to be provided enough protection to enable them to survive the fire by remaining in the structure, at least temporarily.