That's not how this works. The inbreeding generally renders the bloodline into a bunch of hemophiliac morons or congenitally insane weirdos like George III. And these Houses are typically parasites who produce nothing and own everything because their ancestors were good at raiding 400 years or more ago. The days of kings like Charlemagne are long over, and the nation-state is here to stay, and they do not rule by "divine right," and should be laughed into oblivion should they claim to be, as should these inbred blue-bloods under discussion. Today the best you can hope for in a "ruler" is someone who can wave to the crowd with dignity.