Naruto was originally meant to end with the Chuunin exams with Orochimaru being the main antagonist. That's why they thought they could get away with introducing so many charcters. When the franchise ended up becoming bigger than they could've predicted, they ended up with a bunch of characters that weren't meant to have any significance outside of the Chuunin arc. The result was those characters got sidelined hard.
Part of what makes a good author is being able to make use out of the elements (characters, set pieces, history, locations etc etc) over and over again. Being able to use and re-use elements, mix them with new elements, change up the recipe to create a new flavour with a different approach. All that is important. Yes, you might have been forced to lengthen your story but it is still the same elements you made, you should still know how to work with them.
Look at Kubo and Oda. They use their elements better. Kubo uses familiar story elements but goes on about it differently each time, keeping things fresh. First arc, introduction. Pretty simple, show us what different kinds of power there are. Then, Soul Society has the group drop in a fully functioning world with its own internal and external politics, culture and beliefs. The Arrancar arc is also an introduction arc to the new antagonists. Then, the Hueco Mundo arc is similar to the SS arc by design. Aizen is trying to use familiarity to cause others to act in a beneficial way before springing the trap and separating the forces by trapping half the captains in Hueco Mundo. Fullbring arc makes itself look like another introduction arc only to subvert expectations by showing how deep the rabbit hole goes and turning into a psychological thriller. And, finally, TYBW brings us all the elements we were familiar with and flips them on their head. Old new enemies are back, Ichigo has to play defense, things we had taken for granted are taken from us and changed in a way we can recognise but also re-contextualise everything we thought we knew while the world and history are expanded.
Oda, on the other hand, has a brain that baffles. He seamlessly introduces, re-introduces, mixes and re-contextualises elements. Everything looks random at a first glance but once you open the lid, you see a computer program that can add new elements and still work like clockwork. I seriously do not know of a better way to describe. This kind of storytelling requires a lot of love and effort by a very talented person. Those element just do not come together every day. Oda is this generation's best writer.
Kishimoto might have good ideas, but he needed a skilled, disciplined and strict editor who could bring the best out of his writing. Someone who can untangle the mass of ideas in his head and streamline them and piece together a better product.