No, it gives an advantage in one (or two) area of the circuit to make up for the fact they have had dirty air for the rest of the circuit, mainly in the corners where aerodynamics massively benefit a car in front and penalise a following car.
It rewards a driver who has managed to catch and stay close to a very evenly matched car in an overtaking area, the payback being if he gets past, next lap, the car passed will have DRS to mount a challenge back.
Therefore it is completely fair if the passed driver has the skill to stay with the driver who passes him.