Why was classical Greek sculptures considered unrealistic?

Greek sculptures are realistic in form, that means: They always look like whatever the sculpture is supposed to portrait (ex.: if it's an sculpture of a human figure, it looks like a human figure, etc...)

Now, a more accurate description of Greek Sculptures would be that they are "Idealistic. Greek sculptures always portrayed men and women in a very idealist way. All men were very fit, with bulging muscles and very strong. All women were extremely beautiful and graceful.