In addition to cutting three episodes from this series, the producers cut 14 minutes runtime from this episode (shortest ep in history of GoT, true story). So - how much backstory, 'journey time' pan shots or setups better than 'and as the horde gallopped without any intel across one of the hills in the land they never surveyed before they suddenly see entire Lannister army just scratching balls conveniently unprepared' could you possibly fit in those missing 14 minutes? Well, just imagine that the entire Battle of Blackwater Run you witnessed at the end of the episode - from the moment Bronn says "listen" to the end credits - is just 11 minutes and 30 seconds. That's how much story you can tell across few minutes if you give a dragons excrement about your audience...
Meanwhile Brienne of Tarth, unusually tall and strong even among Westerosi men, martial trained since kid, survivor of countless military pursuits, wars and battles, the woman to duel Loras Tyrell, Jaime Lannister and Sandor Clegane, turns out to be just a girl that was taught to sit straight and look pretty, because lil Arya had a few lessons with Syrio back in a day? The truth however is - Arya's reincarnation of Rey from galaxy far, far away