Why was Kaisai not banned more?

Why is this champion not banned more in pro play, Like I feel like IG was a much better team than RNG. Rng imo lost those finals, but IG let Uzi play Kaisai and just Press R after his team gets enguaged on and torn to pieces as they are out of position and punished but still gets to carry the game? Like I dont get it, mobile,again really mobile, AP and AD, kills tanks, kills squishys, melts objectives, hard to burst, o yea forgot poke.

I dont find KaiSai fun to watch, its like watching one team get robbed.