This isn't to be a dick to /u/ZaneWuzHere. This is to capture what WG is either (A)blind to or (B) simply doesn't care:
Every game has a "crutch"; an easy to use, powerful tool that any noob can pick up and use "well" immediately, or something that a player cannot play "well" without. For example, the Grenade Launcher in MW2, or the Rocket Rocket Launcher in Halo.
In your opinion, what is the crutch in World of Tanks?
Your vote: Artillery/Gold Ammo/Platoons/Seal-Clubbing/Premium Tanks - combined.