Blenders are great at freezing fruit because they have a really strong motor that can wick away the heat from the fruits as it works, so there is no risk of over-heating them and turning them into sugary syrup.
Also, blenders are great for liquifying solid foods because their blades can grind things up really quickly. This is why you should never put your hands in the blender jar while it's running or you could end up with big chunks of strawberry in places that don't look pretty!