Iirc that was the original plan by Toriyama. The Cell Games were the end of the series and like you said it completed Gohan's journey just as Dragon Ball completed Goku's. However the editors and money people didn't want their most lucrative franchise to end so we got the Buu Saga and everything after.

It makes sense in hindsight because that whole saga is so unfocused and goes in so many directions til about Super Buu-Kid Buu. He told the story he wanted to tell and didn't know where to go next.