My theory is, that the Kingship among the Noldor wasn't as ideologically well-founded as among Men, they didn't think that their Kings were appointed to this role by the Valar or Eru, nor attributed by them with divine healing power, and made the prosperity or their land dependent on the legitimacy of the King, like the men of Gondor. It was more that they followed whom they held the most suitable, wise and valiant leader. Because of this, and because they could hope that the current king won't die at all, they didn't have well-defined succession laws. This would also explain, how heroic mortals could become mighty chieftains in elven-kingdoms (Túrin), or even marry into their royal house (Tuor). In Númenor this would be impossible for a Lesser Man from Middle-earth.
Have I understood Elvish Succession laws? Did the Elvish Kingship work in this way?
Bonus question: Is it possible, that if Turgon had died, but the City survived, Tuor would've become the King of Gondolin, and as a mortal ruled over tens of thousands of Eldar?
