When I first started this game, I picked CNJ>WHM to start because my friend group were all playing DPS and I figured we'd need a healer (and at the time, tanking seemed scary to me). That was 2.55. One of the things I learned about the game that made me think 'that's cool' was that in downtime when there's nothing to heal, FFXIV healers can throw out damage spells, and they actually deal a fairly hefty amount of damage for a non-DPS role. This was by contrast to my other MMO experience at the time, having freshly fallen off of Snore-lords of Draenor (now THAT's an expansion with a lack of content), which had implemented some changes to damage profiles such that 'deal damage in downtime' was more 'possible', but as with MMO playerbases when changes occur, the players had not adapted to it yet. So there, my experience of healing was 'heal, and if no healing is needed, stand around and wait for some'.
When I started this game again on a new account in 3.2, I decided to grow a metaphorical pair, started as GLD to kill the 'tanxiety', then picked up NIN and SCH because I had heard 'they're hard to master'. And again, one of the things that made me enjoy SCH was the idea that in downtime, I'd use damage to help kill enemies faster. That the fairy wasn't just 'a conduit for some of the healing skills to come from', but a powerful ally whose healing abilities opened up time windows to deal damage safely. I enjoyed healer so much in those days, that by the time I had reached HW, I was 58 on SCH (lots of levelling/MSQ roulettes), and as soon as I reached HW I swapped to AST and mained it for the HW story. By the time I had caught up to the current end of the story (3.3 released by then), I had both SCH and AST at 60. When I decided to make an alt to help a friend's static (and not grief them on loot), I just bought a skip. I'm normally someone who'd rather level a class manually than spend money on a skip, because I detest the idea of paying for a game, and then paying a second time 'to not play it'. But I don't think I'd be able to push myself to get through the story a second time, not with healer gameplay being how it currently is
But enough about me, and more about no-healer runs. I don't remember so much complaining about how 'healers aren't needed' when that one gamer solo healed TEA as a Noct AST (and mouseclicked every button, including Malefic), it was mainly 'amazing that you could handle the HPS checks with only one healer, and in shield mode too, grats! (also please keybind your abilities)' iirc. Part of the reason the TOP run was so egregious was because healers were already feeling 'forgotten by the devs', we'd just come off of the tier which mangled the role population (Abyssos), but also, there is a mechanic in TOP that literally mandates two healers participate in the fight: Magic Number. And despite that 'hard requirement', the fight was cleared because it turns out the 'hard requirement' enforced by that mechanic was not quite as 'hard' as it should have been. As people have said elsewhere, if the shoe were on the other foot, and the fight were cleared with any number of tanks and healers, and zero DPS (because someone found a way to ignore the enrage's DPS requirement), there'd have been an absolute meltdown on reddit and such