Back to the original question, solenoids can be used to drive props directy. The amount of power required to actuate a solenoid goes up exponentially with the throw distance. That's why solenoids don't usually move very far. So since they're small, most people will use hobby servos to perform the same task with greater resolution. I think the only advantage of solenoids for directly driving movement is the simple control. power = actuate, no power = return.
Fun Fact: All of the facial movements in the legendary audio-animatronic Lincoln, at the 1964 World's Fair, were done with solenoids!