To understand the scope for any robot of given complexity, we will discuss it with a very simple example. Consider a robot comprising of one member joined to the base with a revolute joint and a servo motor is connected to that revolute joint which is controlled by a microcontroller programmed to move the member through a certain degrees of rotation. This is the most basic robot which I could think of.
Scope: The motion of this robotic arm is restricted to a circular path. Any task which can be done by the motion along the circular arc can be performed by this robot. Say, we want to draw arcs on sheets of papers or we want to cut them in circular pieces that can be achieved by fitting a pencil and a cutter to the end of this robotic arm.
Limitation: Any point on this robotic arm can only move along a circular path. Any task involving motion other that the circular motion cannot be performed by such robot.
Scope of robots can be extended and limitations can be reduced by adding to the complexity of the robots. One can imagine of the possibilities of motions which can arise by simply adding one more limb to the existing one through a revolute joint and a servo motor. This is a very basic example; in fact, robotics is very vibrant field with infinite scope and an equal numbers of limitations ever reducing.