Other than the very poignant point that Ashe isn't exactly a top tier meta champ...
It's almost undeniable that there ARE champions who are almost indisputably better than others. There may be very few niches certain champions better occupy but over the course of the game, the likelihood that the opportunity for those niches to shine is much lower. In this case, though Fiddles has a great great single target shutdown in his Q and an awesome AoE damage ult, the niches that supports fill often involve more than damage and 1 form of CC (ignoring silence). So "meta" picks are helpful because, typically, these are champions the community believes are the best at the series of niches best suited for the game.
That said, your Ashe was an idiot. People play best when they play the characters they know how to play and play well. Suboptimal picks don't matter at most levels of play and at higher levels of play, there's more coordination so typical meta picks don't apply in the same way. Sure, if everyone was an absolutely perfect player, Fiddlesticks might not be the "best" support nor Warwick the "best" jungler but we're not perfect and these characters fulfill their niches well.
