The reason Faie is superior to Magmar is because of consistency. You can absolutely draft Magmar decks that will crush a run, but doing so consistently is difficult because it has a high dependence on getting good cards in the draft and dodging certain weaknesses in your matchups.
If you get good cards and dodge your weaknesses, you can do great as Magmar! But Faie has the greatest access to common removal and tempo cards that allow her to win games, whereas Magmar has to be fortunate enough to hit the right tools.
Vetruvian is even worse because it has an even stronger dependence on dodging rear-line ranged minions from your opponent. A single buffed ranged minion early in the game and you lose the game. But if you get decent cards and dodge Reva and ranged minions, you can go 12 with Vet too!
Any general can go 12 wins under the right circumstances. Faie just has the easiest and most consistent ability to get there.