: But the Elves of Doriath accepted Dior as their lord and the Elves of Arvernien (survivors of Doriath and Gondolin, joined by other refugees) accepted Tuor as their lord.

: It could be argued, however, that in the last decades of the First Age the old traditions and conventions were dissolving rapidly. The Beleriandic civilization was for all intents and purposes destroyed. Arvernien was too weak to pose any threat to Morgoth and even the ravaged Feanorians were able to destroy that land. Balar became the last gasp of Beleriandic culture, and it may have had a substantial population by the end of the Age, but it was also pretty much irrelevant. What developed on Balar may be the true basis for what happened in Eriador and Lindon in the Second Age.

My impression from history and from personal experience (the Loma Prieta quake of '89), when people are weak, under threat, experiencing chaos, ladership falls to whoever gives the impression of leadership: whoever gets (and keeps) his wits and speaks loudly, tells people what to do. Formal rules of heirarchy and inheritence go out the window. A reputation for courage, ability and luck count for more than pedigree.

As for elves accepting the (temporary, after a crisis) leadership of men, in addition to Dior and Tuor and Earendil, the folk of Nargothrond followed Turin for a while: he had courage and ability, though he could hardly be said to be lucky.