Aren’t smoke alarms enough?

They do different jobs. An alarm tells occupants to leave. A sprinkler puts water on a fire. Modern furnishings burn hot enough that a room can reach flashover in under three minutes, which is less time than many households need to wake, gather children and get out. National Fire Protection Association (NFPA) data has the fire confined to the object or room of origin 96% of the time where sprinklers are present, against 72% where they are not.