No, but that's not relevant.
Okay, you...missed what I actually was asking you since I was actually curious about it - why WHM = PLD not WHM = WAR?
Having asked that (and hoping you address it - I also started a threat to discuss damage rotations):
Which people/encounters/content are we talking about?
Medica 2 spam can handle...a lot. I mean a lot a lot. So without actually requiring any higher skill, the Cyan bar goes a long way. And are we talking about MSQ content or Savage content? If Savages, then the Cyan bar is irrelevant since Savage healers should be in Magenta anyway AND adding more DPS buttons also pushes into Magenta since at that point you have to deal with Savage damage and mechanics (already a higher level) as well as Enrage, meaning engaging with the DPS kit isn't optional. So which content and which healers are we talking about?
Secondary:
Assuming for the sake of argument WAR is an acceptable "lower bound", what would WHM (or any healer, but WHM makes the most sense to me, personally) need to be equal to that lower bound? Again, me personally looking at it, Dia is harder to manage than Storm's Eye since you can track it on multiple things, it's harder to track than a self-buff, and and it can't be stacked (so even overwriting 6 seconds is suboptimal where doing so with Storm's Eye may not be). But Storm's Eye requires a BIT (5 seconds) of prep time with the 1-2. So this is more of a side-grade than anything. Outside of that, WAR has a 3 stack oGCD (Onslaught), and Fell Cleave/Primal Rend vs Solace/Rapture/Misery, which aren't exactly comparable, but are probably somewhat close considering giving WHM a GCD damage burst would require turning Solace/Rapture into oGCDs otherwise they'd have their healing strongly curtailed during their bust (that Cyan bar you mentioned), so the current Lily vs Beast Gauge comparison there is probably pretty comparable.
So turning Dia into a self-buff combo action and giving WHM a 1-2-3 combo...would that be sufficient to make WHM comparable to WAR and thus sufficient to meet the "lower bound" acceptable bar?
...hence my point: Scales are subjective.
We're probably also talking about different things.
For me, a 1 would be "autoattack, the class". The floor is a class where it plays itself (Vanilla WoW Hunter; literally you'd autoattack and...that's what you did for entire boss encounters). You can't really have a lower skill floor than "don't do anything after initiating combat". So that's the absolute bottom end (1 or 0, depending on how we set up the scale). And my scale includes everything about the Job, so for healers, it isn't just the damage side, it's also the healing side. Healing plans add complexity, skills with delayed effects or that involve tracking things add complexity, etc.
My scale's probably also semi-exponential (like the Richter scale), though not quite in that same way (since there's hypothetically not a cap on "most complex possible", so a scale needs to be "semi-infinite" sorta).
I'd rate NIN similar to AST, personally. Mainly due to the burst APM and all the stuff to juggle, though NIN...is hard to measure since the burst is really high up there but the maintenance rotation outside of burst is basically identical to WAR's (self-upkeep buff, gauge burn to prevent overcapping, it just has a Mudra use or two alongside that).
And it also comes down to how you measure difficulty. For example, I measure 1-2-3 (non-branching) as functionally equivalent to 1-1-1, and I consider a 30 sec DoT more complex than a 30 sec upkeep buff (can be on more than one target, harder to visually track on my screen), especially compared to a stackable (up to 60 sec) self-buff. Whereas, from your perspective, the 1-2-3 is more interative and more complex (maybe?), and you probably don't consider Dia to be more complex than Storm's Eye whereas I do.
Scales are subjective.
That was, you might recall...my point.
.
10 - BLM, MNK
9 - NIN, DRG, AST
8 - SAM, BRD, DRK
7 - GNB, MCH, RDM, SCH
6 - RPR, SGE
5 - DNC, PLD, WHM
4 - SMN, WAR
3 - N/A
2 - N/A
1 - N/A
Though...I suppose I need to really lay out in thought what makes each number what it is. Again, with 1 being "rightclick and leave the room", the absolute floor, what is above that and how much for each one... But, it's all subjective.
I suppose I should try formalizing the system. Hm. Maybe something like:
1: Absolute floor of "cannot fail, don't even have to play". Vanilla WoW Hunters in Molten Core auto-attack.
2: Have to actually press buttons, but there's no real failure state provided you are actually hitting things. "FCFS" ("first come, first served", or "use things as they come off CD") Ret Paladin from Wrath of the Lich King.
3: Has failure/suboptimal states, but the punishment is effectively nonexistent, no real choices. EW SMN if it didn't have Energy Drain or Ifrit.
4: Like above, but actually has some choices for optimization, even if they're very minor. Additionally, may "part time" track additional things (party buff utility, healing, threat): EW SMN, WAR, possibly WHM
5: Like above, but has either additional things to track or extra role responsibilities to track or a more complex rotation or situational/proc alterations to rotation or etc: DNC, PLD, probably WHM
6: Like above, but has more than one of those things, and/or a more rigid, less flexible rotation, more tight timings, or more indirect actions: RPR, SGE
7: Like above, but has additional complexity or speed, more esoteric/nuanced optimizations, and a tighter rotation/gameplay with a bit of jank/clunk that must be overcome: GNB, MCH, RDM, SCH
8: Like above, but likely has even more things to track, more clunk to overcome, and some niche and possibly counterintuitive optimizations to maximize performance: SAM, BRD, DRK
9: Much more technical, often with very high APM phases, easy to drift, very punishing on death, and penalty for failure is high: NIN, AST, DRG
10: Highly technical, optimizations are unintuitive or even counterintuitive, very punishing on death, have many openers, reopeners, and rotation possibilities to memorize and optimize around: BLM, MNK
I think that's pretty fair. There's a little room for wiggle here and there (like SMN is borderline a 3, and probably would be if it didn't have Ifrit or holding Energy Drains for 2 min burst windows; WHM is borderline 4 instead of 5 but I feel like the DoT pushes it over into a 5 - if it was a self-buff or didn't have that, it'd easily be a 4; MCH has a lot in common with the 9s, but it just feels overall easier to execute in practice, even if it otherwise shares a lot of their characteristics; etc etc)
I suppose if I added 0 and put the "Vanila WoW auto-attack Hunter in Molten Core there", it would slightly open up the middle, and have some things scoot down (the ones on the borders mentioned above, perhaps), but the list is subjective to begin with, even with a more formalized categorization schema.
Some are just always going to be subjective. Like I find GNB easier to play than DRK (and found it easier to play than pre-6.3 PLD), but others find it very difficult to play. So some things really are just the individual. (For my part, it was always easy for me to tell where I was in my rotation due to how rigid the rotation is, but to some people, that rigidity is what made it hard to play...)