Caster job based around summoning primals, primals that have conveniently established one for each element early into the story: cannot use all 6 elements, take one more Bahamut.

Caster job based around welding both black and white magic, which collectively includes all 6 elements: cannot use all 6 elements, take Jolt 3.

Caster job that's based around paint: can use all 6 elements.