They've pretty much got it covered. I'd personally discount the fact that Jobs are a 'rare' thing since you see enemy humanoids strutting around lobbing fireballs at you and your mates. They've clearly come to power by some alternate means.
That being said, alternate interpretations of events that are not elaborated upon objectively are always good places to derive a 'rare' power source/gift from. Just because an NPC says 'Oh yeah, there's like, one Black Mage in all of Eorzea and he's evil,' doesn't make it true. NPCs have a capacity to be unreliable narrators.
BUT if you go the path of free-form interpretation, it's always in your best interest to research. Lots and lots of research. Because people will doubt you and question you, and needle you about your choice to not be conventional or simple. And, assuming that bothers you, you'll need to justify your interpretation with appropriate lore related history, facts, and theories.
That being said, alternate interpretations of events that are not elaborated upon objectively are always good places to derive a 'rare' power source/gift from. Just because an NPC says 'Oh yeah, there's like, one Black Mage in all of Eorzea and he's evil,' doesn't make it true. NPCs have a capacity to be unreliable narrators.
BUT if you go the path of free-form interpretation, it's always in your best interest to research. Lots and lots of research. Because people will doubt you and question you, and needle you about your choice to not be conventional or simple. And, assuming that bothers you, you'll need to justify your interpretation with appropriate lore related history, facts, and theories.
Please read all the above with a soothing, British accented monotone.