I think it comes down to a hard cap/soft cap kind of thing. In terms of core function a healer has a hard cap of keeping everyone alive enough to beat enrage where as DPS are always chasing a higher number. To an extent (most) healers are as well, at this point we can probably comfortably say healer DPS is a thing, but the level of skill to perform optimal single-target healer DPS is so low (are your DoTs up? Are you nuking?) compared to a tank or DPS they aren't in the same galaxy.
This means that to adjust as a healer is intrinsically less on their DPS than adjusting for a DPS. Why do you think no healer has a gap closer or any movement abilities? WHM and SCH could certainly use them for Holy/Assize/Miasma II but because they aren't punished nearly as hard for disengaging it isn't an issue.
This is a necessity of the healer role in FFXIV, we have to be able to put down and pick up our DPS around healing the raid, but if Stone IV's potency started at 180 and increased by consecutive, uninterrupted casts (or some other still comparably easy mechanic) healers would at least begin to understand the turmoil a DPS faces when a boss goes untargetable, a status effect hits them or they happen to die. I don't want that, it would be terrible, but because we have this luxury to put out comparatively stronger DPS with less focus on it we do, by definition, have an easier time.
Lastly I would like to say even in reasonably easy content like EX primals or Omega normal a part of the healer's comfort is determined by their group. Are you in a competent, knowledgable static? The healer has a great time. Are you with inconsiderate, stupid pugs (not all pugs, I know) who eat every other bit of avoidable damage and don't perform basic mechanics? No one in that party is working harder than the healer.