Why do people say Fiora is weak?

Every since the nerf on Fiora a few patches ago every has been calling her weak. Her banrate has dropped way down and I can't figure out why. Lately, I've been having great success with her in low elo, and I'm loving her, but I'm worried there is something I'm missing. I was wondering why people think Fiora is weak? Does she stop being efficient once you get past gold?