This depends on context. When I think of perfection, I think of it in an engineering and scientific perspective; perfection is a theoretical limit. A perfect turbine would convert the exact amount of energy that flows to it in to the same amount of electricity, as an example.
Thermodynamically, this is impossible because of the second law of thermodynamics; for every action there is a generation of entropy. For a perfect system, there would be no entropy generation, it would just be a direct energy conversion where all energy in equals all exergy out. However, people that design such thermodynamic devices as turbines strive to make these devices as close to perfection as they can within current technological and budget parameters, so as to maximise the efficiency and therefore the exergy of the system.
Following this concept of perfection as a theoretical limit, it shows that there's something to strive for. Just because the limit itself is unattainable does not mean you shouldn't try to get as close to it as you possibly can.