Quote Originally Posted by Brightamethyst View Post
Soulstones are not required to become a job (except SCH and WHM.)

Soulstones are a history of the job and the abilities learned by the previous holders, making it easier for the current holder to learn said abilities. It's possible to become a paladin/bard/dragoon/etc through time and effort and training alone. The soulstone is just a shortcut that lets you skip the years of extra training. (The exceptions being SCH where the fairy is tied to the stone, and WHM where the elementals won't accept a non-padjal without it.)
From a lore perspective, this is correct. Take Machinist, for example - their Soulstone is completely empty. In theory, an individual should be just as accomplished with or without the stone equipped, since the stone provides no knowledge or skills whatsoever (rather, you're wearing it as a courtesy to pass your own skills and knowledge on to future bearers of the stone).

I would guess that the others are the same way. It's not impossible to learn the job skills though research and self-discovery - having them pre-packaged in a stone just makes it easier and more convenient to pass knowledge of these skills. I'd argue that this even applies to SCH and WHM. In the case of SCH, a Soulstone is a convenient place for the fairy to dwell, but it needn't be the only possible such dwelling. An animated puppet, like the one you earn at the completion of the Anima questline, could serve, as well. (As for WHM, I forget what makes their Soulstone so special and unique - but recall that Amdapor in its prime had PLENTY of folks wielding White Magic; a single stone couldn't possibly account for that, so it's clear the skills can be learned without bearing that specific stone, or likely any stone.)