It wouldn’t. FFXIV class design is literally hinged on classes being very unique with very little overlap, typically only with the role abilities or the job of the class. Then adding onto that, there exist support classes that are meant to buff stronger damage dealing classes, or your group at large and that justifies them having a spot in a group. Like Ninja can be garbage for its own damage but people will still bring it because Trick Attack is just so ridiculously powerful to add 10% damage to everyone’s damage. For healers, Astrologian will have less throughput healing than a White Mage because the White Mage is designed to be the best healer. Astrologian heals effectively but trades some of its healing power for the ability to buff members of your group with cards that function like Roll the Bones. So they trade some capability for utility.
WoW has an issue where every class feels they should have an equal shot at being number one DPS regardless of how much utility they bring. Then you bring in specs and it gets more troublesome. Whereas I don’t have DPS spec Astrologians in FFXIV. They’re playing Astrologian, they know their job is to heal and aren’t given some goofy setup that makes them become some weird variant of Black Mage.
FFXIV tends to balance classes with a power budget, if you have a lot of utility, you tend to have less damage. If you’re built around just doing damage, you have limited utility. A good example of this is the Red Mage where it can bring instant cast resses in combat and offheal in a pinch, but its damage is never going to compare to a Black Mage who only has damage dealing going for them, or any actual healer.