Because if Ash won every single battle in the entire series then it would be about as fun to watch as watching paint dry now, would it? There’s gotta be some stakes thrown into the mix and the World Championships is THE perfect opportunity to throw in just that.

Heck, not even Yami Yugi or Yusei Fudo (sure, he fell off his D-wheel during his first duel against Kalin but he was most likely gonna lose anyway) from the Yu-Gi-Oh franchise won every time (well, unless your name is Yusaku).