Class => Job => ???

[Sandpark]

they can balance this, when they change every single skill when you equip a job crystal.

for example you play the base class and all your skills are in the "class" layer. now you equip a job crystal on that class and all your skills in the "class" layer are gone, instead you get a whole pack of new skills in the "job" layer. that can be the same skills, same anmimations, same potencys, or adjusted potencys or whatever and of course new skills.
now you can balance this job without touching the base class and you can add as many jobs as you wish on that same base class.

I recall thinking the same thing before but didn't say it as simple or concise. Nice, but idk if SE wants complexity over simplification.