Is taliyah lonely ?

Why riot keep nerfing taliyah again and again.. If champions like zed can kill anyone with his ultimate and can have higher cooldown rate in R. Why can't taliyah couldn't have any adavantages. Her R cooldown rate is low. Her passive do no damage. Her W do too less damage. Come on riot. Nerf champion like katarina and fizz who has sky high win rate. Not taliyah who has lower win rate.