The Pigeonhole

[Nahara]

Because that's kind of the point of Jobs. Classes are versatile and able to do other things besides it's designated role if you pick and choose the right gear and cross-class abilities. Jobs prevent such versatility but greatly improve your capacity to perform it's given role.

Conjurer can be a viable magic damage dealer, but White Mage will always be a healer. Lancer could probably pull off being a tank, but Dragoon will always be a melee damage dealer. The only problem is that such versatility with classes can't really be exploited in party settings, since you need to be really good in your role in order to not suck and die and probably make your whole party die. When you're walking into Titan EX, nobody's really going to care how good your healer Thaumaturge is when the Scholar and White Mage perform that role a thousand times better and with less effort.

[Gooner_iBluAirJGR]

Conjurer can be a viable magic damage dealer, but White Mage will always be a healer. Lancer could probably pull off being a tank, but Dragoon will always be a melee damage dealer.

Stop talking nonsense please. Conjurer as a damage dealer? Because Raging Strikes and Blood for Blood will turn them into
a viable damage dealer? Thanks for the offer but I'll have to pass.

Lancer as a tank? Skull Sunder and Savage Blade will turn them into a viable tank? Thanks for the offer but I'll have to pass.

[Nahara]

Stop talking nonsense please. Conjurer as a damage dealer? Because Raging Strikes and Blood for Blood will turn them into
a viable damage dealer? Thanks for the offer but I'll have to pass.

Lancer as a tank? Skull Sunder and Savage Blade will turn them into a viable tank? Thanks for the offer but I'll have to pass.

In low-level dungeons, I've main healed on Arcanist and tanked on Pugilist. It worked but it was nowhere near as effective as just sticking to your given role, and that's the point. Right now, it's so much more effective to just stick to your role than to try and branch out into some other role and Jobs only emphasize this by making you even better in your given role. This won't always be the case, though, as Yoshi-P apparently plans to implement a "Hybrid" role into the game at some point; how that eventually works out (if it even comes out in the first place) is still up in the air.