"Pure Healing" a la Cure spamming is a boring, unengaging design paradigm. D&D learned it decades ago. The cleric used to be either the person who drew the short straw or the rare person who just wanted to roleplay a priestly type. If your combat decision making process is something you could teach your dog to do, most people don't find it fun. This isn't to say that a simplistic healing model is a design flaw. It's a design decision. When you take a mandatory chore like healing or tanking and make its management low-stress, you can shore up the engagement elsewhere. Like, oh, random example off the top of my head, damage dealing. Or buffing! Or debuffing. Or battlefield control.

Healing in FF14 is of the trained dog variety. Spamming more outgoing damage on the party does very little to modify the decision tree, if anything at all. There are a lot of directions to go from here. Magic Missile and Cure Moderate Wounds until you lapse into a coma is not fun.

HeaLErS ShoULD HeaL onLy is from 1985. We've learned a lot since then.