JJK reinvented jumpings, I never said it gave birth to them. Ffs, Demon Slayer had the whole corps jump Muzan. JJK only made it more relevant. Also, a lot of mangas tend to make ways for 1v1s to happen rather than having the logical solution of jumping. Another thing is old mangas also utilized reverse jumpings more than jumpings, Madara vs the shinobi alliance for example, or Aizen vs the Gotei 13 + Vizoreds. It isn't common for an anime to have a jumping actually work without other outside factors contributing, going back to Muzan vs the Demon Slayers, they drugged Muzan multiple times in order to win, and with most of these fights they jump the enemy because they know without a shadow of a doubt they can't win otherwise, like, they have 0 wincons outside of teaming. Yuji and Nanami vs Mahito broke this because Yuji actually held his ground for a bit against Mahito until Nanami came, then they f***ing wailed on him, same with Yuji and Todo vs Mahito.