why was kai'sa buffed

kai'sa was a perfectly balanced champion with one of the highest damage and surviving kits among adcs , before the buff a good kai'sa player could really do alot , like a jinx or good vayne ... now shes just autoing a tank and bashing them into the ground she didnt need this buff ... i didnt ban her at all because she was a balanced champion i know that because i played her my self , but now i need to ban her because she just dominating the maps ...

buffing kai'sa at that level was a mistake , i know shes gonna be nerfed in future patches for sure but why would u buff her just to nerf her in the future

ps : if the win rate was low it was because people who never even played a marksman in their life were just picking her and playing her while not knowing her kit or the positioning and etc for the marksman