Why are they called Jobs?

Just curious, why are the Jobs, called such. I understand from a FF history perspective why, but where does it really fit in the world itself?

Maybe, we could see some Job specific quests..reoccuring themes commissioned by the GC's or different groups within the city states that arent GC specific.

WHMs going to camps or hamlets to heal the sick and injured..paid by whatever the local authority there is.

BRDs going to taverns or performing for the rulers of each city state.

DRGs, WARS, MNKs being used to hunt down certain kinds of creatures specific to their type of skills, job specific quests that dont allow for cross-job/class using. Edit note on this: Maybe we may even see job specific traits to follow the classes. XI had certain things, PLD had Undead Killer, WAR had Vermin Killer I think? DRG had Wyrven Killer...all they basically did was terrioze the corresponding monster type.. BLMs had Arcana Killer..such as Bombs and the like.

PLDs can defend a group of npc refugees running from a horde of soldiers or random monsters, not so much about the killing the creatures, but keeping yourself and the npcs alive.

I realize some of these ideas are in guildeves and GC leves..such as keeping the npc alive. But again, its something you can do on any job and doesnt really have anything to do with how good you are at using your PLD skills.

But you get the idea, yeah?