I had a psychiatrist once who was a fan of One Piece and when I had him explain it to me, it didn’t sound like he enjoyed the plot as the main course per se but enjoyed that the characters were consistent. That he could pop in around any arc at random and have an idea of what’s going on. Luffy is rubber, Zoro has his sword, etc.

He viewed it more like a soap opera you could tune into, rather than something you view from start to finish.