During the winters in areas that get snow, this practice will protect damage to both the wiper blade (the rubber itself) and the wiper motor.
Even with a small amount of snow, if it becomes ice overnight, it will cause your wiper blades (rubber) to stick to the windshield glass. There is a possibility that it will rip and a portion of it stuck to the glass if you try to pull it away from the glass when still frozen. In addition, turning on your wiper blades (accidentally or intentionally) while not fully thawed may damage your motor as it is trying to move not only the weight of the blades and wipers (which is what it was intended to do), but also the friction and resistance of the blade against ice or the weight of snow.
If your vehicle type permits raising the blades into the air, you can safely remove/scrape ice from the windshield and the blades, and then put them down and use the wiper blades normally.
This practice keeps them from freezing to the glass, which can easily damage the edge when you pull them off, or wreck your wiper motor if you accidentally start the car with the wipers left on.
In case you forget and find the wipers frozen down, keep a small squeeze bottle of ice-melting wiper fluid in the car. Squirt that along the edge of the blade, wait a minute, and the wiper comes free.