
Based on the initial job quest for SMN and SCH, if you're going strictly by those:
Summoner -- Easy, if you hold to the main scenario quest too. All it requires is that you become attuned to a Primal's energies without being Tempered (most commonly by defeating it in battle), then summon and defeat its egi to bend it to your will. Any Arcanist with the Echo can, therefore, be a Summoner.
Scholar -- The quest has you uncovering a set of tablets from Nym that describe the art at the behest of a marauder of the Coral Tower. At the same time, you end up freeing from a locked box one of the faeries of Nym, which is apparently quite a rare thing. So, it's tricky for more than one person to be a Scholar if you're playing strictly to the job quest, as while multiple tablets and documents could be found, the faeries themselves are seemingly rare.
IMO, I think people should play what they want to play, especially since the written lore ("there's only one dragoon") and the game system abstraction of lore ("anyone with enough time and effort can be a dragoon") differ so severely. We all pick and choose pieces of the main scenario quest and its lore that work with our characters; for instance, some choose not to have the Echo, even though the MSQ makes it abundantly clear that many people have it and certainly all PCs do. Conversely, almost every RPer dispenses with the "you're the personal envoy of your city-state" part of the MSQ, because it's far too centered on a single character. On that basis, I don't see any reason why people can't view the job quests similarly -- take what's generic or can be easily made generic from the quest if desired, then fill in the blanks with what works narratively. You can even take this one step further and view the job quests in the same way as the non-generic parts of the main scenario quest. In this model, the job quests are something that Some Great Hero did, and in doing so, opened the doors to a revival of the job through other means.
That said, it just seems sensible that people who have jobs that have been historically forbidden (Black Mage, White Mage) or extremely restricted (Dragoon, Scholar) would keep their abilities quiet to avoid all the IC consequences that can come about from that. From zealots wanting to "purify the heretic" to supplicants begging for aid, advertising you have some rare power seems imprudent. I'm not saying that's how it has to be played, but it seems to me that a newly minted White Mage (through whatever means) wouldn't go advertising that fact.
In practice, I don't RP any of the jobs. My character's an especially talented and skilled user of magic. That her spells may have similarities to those vaunted abilities of the legendary Jobs of Eras Past is chalked up to coincidence.
Summoner -- Easy, if you hold to the main scenario quest too. All it requires is that you become attuned to a Primal's energies without being Tempered (most commonly by defeating it in battle), then summon and defeat its egi to bend it to your will. Any Arcanist with the Echo can, therefore, be a Summoner.
Scholar -- The quest has you uncovering a set of tablets from Nym that describe the art at the behest of a marauder of the Coral Tower. At the same time, you end up freeing from a locked box one of the faeries of Nym, which is apparently quite a rare thing. So, it's tricky for more than one person to be a Scholar if you're playing strictly to the job quest, as while multiple tablets and documents could be found, the faeries themselves are seemingly rare.
IMO, I think people should play what they want to play, especially since the written lore ("there's only one dragoon") and the game system abstraction of lore ("anyone with enough time and effort can be a dragoon") differ so severely. We all pick and choose pieces of the main scenario quest and its lore that work with our characters; for instance, some choose not to have the Echo, even though the MSQ makes it abundantly clear that many people have it and certainly all PCs do. Conversely, almost every RPer dispenses with the "you're the personal envoy of your city-state" part of the MSQ, because it's far too centered on a single character. On that basis, I don't see any reason why people can't view the job quests similarly -- take what's generic or can be easily made generic from the quest if desired, then fill in the blanks with what works narratively. You can even take this one step further and view the job quests in the same way as the non-generic parts of the main scenario quest. In this model, the job quests are something that Some Great Hero did, and in doing so, opened the doors to a revival of the job through other means.
That said, it just seems sensible that people who have jobs that have been historically forbidden (Black Mage, White Mage) or extremely restricted (Dragoon, Scholar) would keep their abilities quiet to avoid all the IC consequences that can come about from that. From zealots wanting to "purify the heretic" to supplicants begging for aid, advertising you have some rare power seems imprudent. I'm not saying that's how it has to be played, but it seems to me that a newly minted White Mage (through whatever means) wouldn't go advertising that fact.
In practice, I don't RP any of the jobs. My character's an especially talented and skilled user of magic. That her spells may have similarities to those vaunted abilities of the legendary Jobs of Eras Past is chalked up to coincidence.

The Freelance Wizard
Quality RP at low, low prices!
((about me | about L'yhta Mahre | L'yhta's desk | about Mysterium, the Ivory Tower: a heavy RP society of mages))
Quality RP at low, low prices!
((about me | about L'yhta Mahre | L'yhta's desk | about Mysterium, the Ivory Tower: a heavy RP society of mages))