Also known as the Naruto formula. Start off with grounded battles with melee weapons and fists. Jutsus and magic that does small damage and might only wound and not kill. A few fireballs and are out of energy. Strategy. Tactics. Low amount of chakra or energy pools even for powerful characters. Secret and forbidden techniques like shadow clones that are impossible to use for all but the most skilled ninjas. Shadow clones when used often can drain your energy and kill you. Only one ninjas in history can use water techniques without being near water. Straightforward story. Countries are at war. They use ninjas and child soldiers in a 'Hunger Games' or 'Battle Royale' to avoid an all our war.
Fast-forward and you have actual god powers. Planet sized jutsus and attacks. Talk no jutsu. Everyone getting revived from the dead. Shadow clones are used by every other character. Characters can throw moon sized fireballs multiple times. All characters can use water magic without a source of water. Secret alliances and loyalties changing like the weather. Characters with secret lineages and alien heritages. Everyone has magic eyes. Even more tailed beasts. Apocalypse scenarios. New levels of plot armor in being reached in a narrative. Naruto is the son of an ancient god yet it was all hard work.
The ends of Naruto and Attack on Titan are very similar. With the ancient lineages and powers that descend from an alien being. Every famous ninjas or titan being revived for the final battle. Talk no jutsu and Eren practically breaking the fourth wall when talking during the later chapters. Power levels bloating from grounded fights to planet sized conflicts in one battle. Political councils or speeches that exploded into huge fights or ambushes. The stories just bloated and grew and grew. And they became an apparatus for "big" moments like explosions, huge fights, assassinations, last stands, last second saves. Regardless of whether or not any of it made sense with the plot. Nor if the scales of the conflicts was consistent with the first halves of the mangas.
I think Isayama and his editors were making too much money with the story and just kept expanding it until it just collapsed on itself. Sure they never to the absurd extremes of Naruto with the filler and movies and gargantuan expansion of the story. But I remember reading through Attack on Titan and thinking very early "this story is going to get out of control like Naruto unless they have everything planned out". And it seemed like they had no idea where to go once they got beyond the walls and off of the island.
