We've been through this before, when you start a game you pick either Conjurer or Thaumaturge.

With Conjurer you get:
Fire, Blizzard, Aero, Stone, Thunder, Water.

With Thaumaturge you get:
Scourge
Banish

You are never forced to, asked, or told to either guild until much later in the game, you can argue canonical nature all you want if the information is "obscured" and once you just start the game, you see these two, and which one you think is the Black Mage? and don't lie, Conjurer (SE is also to blame with their retarded naming) has all the indications of being a pure black mage, yes later you get buffs and heals, but you do so with both, but I'm not arguing what you get later, this is all about first impressions, and unless you read all the random Wiki crap you really don't know what you're getting into the first time around, you can draw symbolism and Naming into this all you want, the statement stands, people don't come here to perform analyses of the mythos, they come to play a game, and the abilities provided to them at the start are misleading to the purpose of jobs themselves.