It seems to me that the Fisher King/Messainic mythos is about a person dying for others. Without the other people, the Fisher King is nothing but an individual connected to the primal undercurrent of the earth - they need a community and society to make their sacrifice mean something, otherwise any victory they achieve is Pyrrhic in nature.

Thus it seems to me that interpreting the Fisher King story to mean that this person is the be all and end all with noone else having any greater importance overlooks what the role of the Fisher King is. If Rand were to win, but Elayne, Egwene, Mat, Perrin and Nynaeve were to have failed in their individual quests, I would say that the world would perish anyway, though not at the Dark Ones' hands. As Min's vision showed us so early on in the series, without the others working for the greater good, Rand's spark of light could not match the darkness, and only when the other sparks started joining with him, were other points of light able to converge so that the light could be equal to the darkness.

That vision indicated that the Dragon Reborn is a necessary condition to win Tarmon Gaidon, but the roles of others can be necessary, as well. Rand's felt this multiple times in the series, but the earliest IMO was during "The Great Hunt" - all Rand knows is that if he didn't go and try to rescue Egwene, some aspect of him would have failed. I'd argue that he was sensing the necessity for him to save her in order to acquire a necessary supporter to make his mission succeed. The Pattern may very well have endowed Egwene, Mat, Perrin, Elayne, Nynaeve and Min with their gifts and advantages so that each could be transformational figures in their own rights without Rand having to be everywhere at once.