Turns out Vayne top isn't broken as Reddit anticipated.
It's understandable that top lane players aren't happy when they see Vayne in their lane - but significantly exaggerated impact, yeah.
One of the really understated facts (good or bad) about role select is that players have sorted themselves based on what kinds of laning experiences they want to have. It doesn't matter which role Seraphine is highest win rate in or best in pro play in - players who like Seraphine as a character almost always queue support. It doesn't matter if Darius beats Teemo (he doesn't right now, but there've been many states of the game where he did) - Darius players are queuing up to have the melee 1v1 experience. And it doesn't matter how many mages are viable in bot lane - players who want to play them are mostly not queuing into bot lane.