The power dynamics have really never changed. A medieval king and a modern dictator function almost the same way, an all-powerful figure running a nation by decree. The concept of honor was important but the whole system was also very Machiavellian. The ruler wielded absolute power over everyone and everything in the kingdom, including the powers of life and death. So to answer the question of "why did they put up with it?", it was because if they dared to defy the monarch openly, they were taking their life into their own hands. A monarch is powerless without followers, but if just one person steps out of line and is beheaded, the rest will be much more hesitant to do it again because they know the risks they take. So the knowledge that their entire fate was decided by the monarch was a powerful tool in keeping people in line. And yes, there was a lot of scheming and plotting behind the scenes, but at great risk to the individual involved. And for the last sentence, people obeyed so that they wouldn't be next.