Note that I do not agree with the concept, either. I am also the product of a modern Western democracy, which kicked out royalty at gunpoint some centuries ago. (In fact, some of my ancestors were oathbreakers to that King, and fought in the Revolution on the side of America).
And even that form of royalty was very different from the ancient form I am describing. I think that when we Americans think of a King we think of a corrupt and cruel absolute dictator like Henry VIII. But the original concept - something that fragments of our oldest folktales and legends only hint at - was very different.
You even get hints of that in the Iliad and the Odyssey. Menelaus was king not because he was the son of a king (Atreus) and the brother of a king (Agamemnon) but because he was married to Helen, who was born a Queen. It was not just hurt pride and manhood that impelled him to get her back - she had taken his right to rule Sparta with her when she fled to Troy with another man. He did not just let her live after the war - let her live and took her back as his wife!
And look at how desperately every young blood in Ithaca pursued Penelope when it looked like Odysseus would not be returning from the war. There are hints of a matriarchy carrying the royal right there as well.
There are many hints in the oldest Greek myths and legends that a King was once the man married to the Queen - and that she could sacrifice him to the gods if her people needed it. And that the royal line was carried through the children of the Queen, regardless of who the father was. This might have been why the gods were so horrified when Agamemnon made a sacrifice of his elder daughter (who would have carried the royalty rights of her country), and why his wife felt she has every right to take on a new ruling husband while we was away at Troy AND to kill her old husband in turn when he finally returned from the war.
Some scholars believe that the culture of that area was once a matriarchy, which changed to a patriarchy when the Myceneans invaded. There was a turbulent time when those two systems met and blended to an extent before the patriarchy came out on top - and that happened to the be time of the Trojan War. Both the Egyptians and Hittites spoke of the invasion of the Sea Peoples, and the Hittite sources (which actually name not only Troy (with a different name, of course) as the capital of a Hittite vassal state but also name one of the leaders of the invaders with a name remarkably close to Atreus) are especially valuable sources of information about those world changing times.