Managed so so much pure stupid in an episode again.
Greyworm goes to a meeting, situation at start of meeting, conquerors won Kings Landing, the city is destroyed, most of it's people dead, thousands of dead bodies in the street but they have thousands of people inside a city of reinforced walls, etc. So the rest talk, they elect a new leader in Bran........ so the situation is they still own the city, they still have thousands of highly trained people in their army inside the city and if the rest of them want the city they need to fight them. It's frankly silly to believe the northmen are a large army after everything that has gone on.
But regardless, they voted in a new king, with basically no authority to do so (as they didn't currently reside on or control the throne) and they just left?
So if Ghengis Khan rocks up to a city, they say well we're in here and we're not giving up, so the people outside vote and elect Ghengis Khan the new ruler of the city, so the people in the city just say sure, okay, makes sense, and leave? That's essentially what happened.
Even without that, if a kingdom can just say you know what, no thanks, I'm done, then what power does the 'king' have. THe reason there has been a ruler of the 7 kingdoms is because some lord decides they want to rule more land so they go and conquer other kingdoms. They keep power by having an army stronger than any other kingdom, they were conquered. Voting in a king with no army and no power over the other kingdoms is entirely meaningless. Without an army, which he doesn't command, then he's an empty vessel on a throne with no actual power.
Go make the Stormlands pay their tax "well they have an army, and we don't"....