Except she originally wasn't immune to attack speed slows. She just needed to be stopped in a way that's unconventional. Build a frozen heart and a randuin's omen and you're already countering her mobility, which works as one of her greatest strengths. Her ability to kite and pump out sustained damage is what made her strong. She's still squishy, anything with point and click cc ruins her, she doesn't build enough crit to remain entirely relevant late game, slow her attack speed and you not only ruin her damage output, but also her mobility, and apply grievous wounds to ruin her sustainability.
After the nerfs, vision denial, slows, her dependence on her support, and the inefficient changes to her core items just fucked her over and as hated as she was when she was relevant, her current condition isn't ok at all.