Jobs were not created to phase out classes.
That's what they've done, though. No one wants an Archer when they can have a Bard (especially when you can have 3 before they cap out in usefulness and each one gets Rain of Death). No one wants a Marauder when they can have a Warrior. Nobody would ever dream of inviting a Pugilist when they can have a Monk. Conjurer over WHM? What're they going to do that a WHM can't do better, weaponskill? The only one with a reasonable debate is THM over BLM in Ifrit pugs for Sentinel/Raise.

But classes are superior for soloing!
Is only partially true. I'd never go Marauder if I'm healing to full with every WS combo I do , stunning everything in my area, and having every damage mitigation ability and then some on my bar as Warrior. I'd never go CNJ when I get every spell I had before along with Holy and REGEN. Other classes are still better for soloing, I'd say, but that's still 2 jobs that far outshine their classes in their explicitly stated realm of superiority.

Whether people want to admit it or not, classes are no longer relevant. It really bothers me, and this sad excuse of a carrot they're trying to dangle in the form of pretty looking gear is almost insulting to people's intelligence. "Hey bro can I come Pugilist instead of monk?" "What why? You'll lose a bunch of useful tools for our dungeon runs and a ton of dam-" "CHECK THESE GLOWING BLOCKS I'M BANGIN" "Oh bro, don't even worry. You're coming pugilist forEVER now. Man I can see forever in these things..."

At least they're good for idling around town doing nothing, which is admittedly 60% of the game's experience.