I think it’s the same reason he is not played in norms/solo q but played lots in competitive. He’s a champ that if he has his team and support playing around him can carry hard. But if his support doesn’t know how to play with him, he is useless. Which contrasts heavily to champs like Kai’sa or Xayah with lots of self-peel or options. He is somewhat similar to Kalista in that sense