There are a few reasons why a fire alarm strobe is installed within the system. When the smoke detector goes off, that means a lot of smoke is being emitted, and it is imperative people get out of the building immediately. Smoke is even more dangerous than the flames. But the problem is, usually the smoke will be too thick to see and make ones way around. Here, the value of the fire alarm strobe is apparent. It helps guide people to safety by beaming light through the smoke so people can navigate their way to safety.
Fire alarm strobes are not only useful for lighting the way, but for those who are handicapped of hearing, a strobe is able to alert them of danger, where fire alarms are unable to. The pulsing light is able to wake up sleeping people or elderly people who are hard of hearing. If the strobes are placed along staircases, they can help people make their way along the staircase in time of poor visibility from all the smoke.
As useful as they are, most home units of fire alarms do not come with strobes attached, since standard regulations don't require them, and they add to the cost. If you want strobes installed, they can be found and bought online or at home appliance stores. It all comes down to how safe you want to be from the threat of fire. A strobe is a very useful addition, but so is every part of the early warning system in the overall fire alarm system (like the smoke detectors and the alarm horns), and having them all working properly at all times, is the most important thing.