There is an art to the sequel series. Being able to craft a story after the end of a major franchise is an uphill battle that requires a certain amount of finesse. There is a lot of balance that happens in a sequel series. Making an interesting plot while not wholly relying on nostalgia and allowing characters to continue to develop is actually incredibly difficult. Basically, it's hard to make a series not feel like bad fan fiction. Dragon Ball Z managed it quite well for the most part because the seeds of it were sewn back in Dragon Ball, with Goku deciding to marry Chi-Chi and Piccolo swearing to return.
Source：https://www.cbr.com/naruto-part-3-better-idea-than-boruto/
