Except they were shown to wield virtually ALL political power in the empire in both the 22th AND the 24th centuries; and much supports this for the 23rd, as well (in this era, though, the smooth forehead klingons did seem competent; they at least had a vocabulary consisting of more than 100 words+snarls). This is the opposite of a quarantined 'societal pocket'. Except the klingons WERE shown to be stupid (the gang of bikers 'macho' flavor). And not even close to 'efficient'. That's why they building and having a high-tech interstellar empire lacks credibility. A 'stable' society declines, in actuality. Look at the chinese and their lacking mastery of knowledge and skills their ancestors acquired and mastered, by the time the europeans arrived.