Good point. Although I suppose you might still want to be home rather than running it while you're at work or otherwise away, to have a chance of grabbing the extinguisher and/or calling the fire department before your whole home is lost. I'm not sure how common it is to have smoke detectors automatically notify the fire department, and I expect there's issues there similar to burglar alarms, with false alarms being far more common than real ones, which affects response time.