What is the be Healer?

[Sleigh]

SCH's deployed shields weren't needed in A1S and A2S even at launch. I know because I cleared those fights with a WHM partner running AST in Diurnal before ilvl was inflated.

For A3S, the mechanic that supposedly requires shielding is Cascade, and you can't deploy Adlo for every single Cascade in A3S, so if this kind of shielding was needed the fight would be unbeatable. The only shielding you can keep up for all Cascades is Succor and the amount of shielding provided by Succor is slightly inferior to what is provided by Aspected Helios (by 7 potency, I know, but since we decided to split hairs in here, I'll give you that).

I can't vouch for A4S, but since there have been clears with Noct. AST instead of SCH, it's pretty much a given that Deployed Adlo is not required in there.

It was a combination of Succor/Soil/Super-Virus/Deployed Adlo. Needed one or two to survive in i190-i200 in combination with some combination of INT down and Storm's Path and misc debuffs. AST makes that moot though since it can Disable all of them and give a Soil equivalent for half of them. In fact, the big strength of SCH is most of its tools aren't needed to hit a boss, and annoyingly in HW there's been a decent amount of attacks you cannot mitigate via Path/E4E/Reprisal/Virus/etc because the attacks are immediately after a phase shift, or otherwise don't come from an enemy you can target. Basically, T9 Megaflare equivalents.

I mean, the fact that there are Noct ASTs clearing A4S with a WHM partner (there are what, two of them so far?) doesn't prove any viability or being as good or better. It means it's possible. Noct AST is garbage compared to SCH, we all know this, in terms of total healing output, mitigation, consistency, and DPS. Noct AST's barely comparable to SCH while missing a fairy, plain and simple (I'd argue fairyless SCH > Nocturnal AST even, if you just mean pure healing). In something like A4S, you need SCH or Noct AST to survive the final Mortal Revolution. Even with deployed Adlo and Soil, everyone except tanks goes down to 1-2k HP in full i210.

I'm actually not sure why you're arguing what you're arguing. This is a topic about what the BEST healer is, not the, "Are all healers viable to clear content?" topic. SCH's the best right now, or at least, the most irreplaceable, because it's the best shield healer, the most clutch, and the "best" at DPSing in most environments for multiple reasons unless it's truly a dummy phase. Farm, progression, speed runs, doesn't matter, you bring a SCH to everything because you'll clear faster and safer than without. It's a broken class. It's been broken since 2.0 and it's arguably even more broken now because at least there were only two healers to choose from in 2.0.

This is basically turning into the healer version of, WAR isn't OP, both PLD and DRK have cleared A4S, they all have their merits! Nope, you always bring WAR unless you like to gimp yourself, otherwise you lose too much; not just DPS, survivability too. Same with SCH.