Rewatching Bakuman, the protagonist within the first episode said that the Japanese population (especially the younger demo) is shrinking. Which meant they probably cannot reach the number one status as a mangaka, while citing Dragon Ball and One Piece as the gold standard.
The most popular Shonen Jump mangas in history (1970 - 2025) ranked based on Table of Contents (ToC) data. Find out which mangas, such as "Naruto", "Dragon Ball", "Fist of the North Star", have supported Shonen Jump over the years!
www.jajanken.net
People had said shonen jump sales decline after Dragon Ball/Slam Dunk ended. I do wonder how strong was the competition when One Piece joined the fray (since I am not particularly known all those old series). But being an assistant to Rurouni Kenshin series. Oda must have seen what the summit is like since that is the series that is top of Shonen Jump post Dragon Ball/Slam Dunk era.
And how quickly did One Piece rise up. One Piece came out in mid 3rd quarter of 1997, and by the 4th quarter of 1997 it reached the number one status, knocking down its mentor series Rurouni Kenshin to number 2. And then basically reign as number one since then. 2005, Naruto barely squeak in the number one status. I split that year in 6 parts. They tied for 1st once, Naruto take the top 3 times, and One Piece 2 times. So it actually pretty close.
Since then, many series had taken the number 2 and number 3 spot. But One Piece is still at the summit of Shonen Jump.
I have been tallied the ranking in my own system to find new series that I have missed in the last decade to read.