Vayne OP 100% pick/ban in World's! Oh wait, that's not true... She might not be completely balanced, but as long as we're talking about ADCs, how about the highly contested Tristana or Sivir pick? How about late game hyper carry Jinx? Do they all need nerfs? These are the picks that are winning matches at the highest level of competitive League right now, but Vayne is relegated to the likes of Twitch and Graves as a viable pick. I wonder why that is.
Vayne is in the spot that she's in because Riot can't nerf a champion for her complete dominance of the lower ranks of solo queue since she holds next to no advantage in the upper tier. There are Vayne mains in World's right now that know that she does not hold the kind of power they need to win games, so they don't even pick it. There is more than enough point and click CC, Gnar/Malphite-like ultimates, pulls, hooks, dashes, and stuns to put an end to any kind of Vayne dominance in League of Legends. It's really just about how your team decides to deal with her. Her kit is a completely situational kit where certain circumstances have to be met for her to use it all to the fullest potential. She's not getting escape resets or movement speed boosts on kills or spell shields or support saving ultimates. She just scales well with an on-hit item that few markmen build and has a 3-hit effect that deals unique damage. Vayne is just as killable as any other ADC. And apparently not nearly as viable competitively.