Your technically the highest ranking officer during the assault on the forts and you command the men on the wagon ambushes. (Though same for the stormcloaks.)
Actually Ralof was.
Dude by killing dragons you saved skyrim. The nords acknowledge strength above all. And how has Ulfric proven himself to be a great leader? Some examples where the dragon born was not the catalyst please. Cuz I mean let's be honest dragonborn makes everyone look good. Outside of the markarth incident(which was clearly a plot by Ulfric to get sympathy for his cause) he has got nothing.
Nords value strength, but they're not stupid. They're not gonna make some random guy who doesn't even know their customs King. How are you this stubborn? Dragonborn is a killing machine, not a politician or one who can lead a nation and its armies.
Dragonborn isn't even guaranteed to be a nord. They're not gonna let a khajiit be High King...