Oh no! Jobs meant to do multiple things would be desired due to their ability to do multiple things, particular when a lot of one thing isn't needed!
When your primary, designated job for healing does one thing well, and offers little else yeah. It's a problem. WHM should be the go to being a 'main healer'. And if you want to go without it, invite more hybrids or other jobs that help reduce damage.

ToAU's exp/meriting system was nothing short of a pox on the game and a serenade to mindless melees. Why do you think I want a variant endgame and more variant forms of job play?

I'm not saying remove RDM and SCH from the healers list completely, but tone down their position so that WHM is still a consideration even when their curing ability is overkill, and give RDM and SCH more availability and viability in differing departments so that inviting any combination of these doesn't seem so counter-productive. (Same for giving WHM something to offer in lesser cure Demanding situations.) I'm in support of this for Melee jobs as well.

There shouldn't be any 'one right answer' to approach a situation, regardless of its difficulty. The idea of what makes an MMO so worthwhile is that it is so large and variant.

SE has been doing a fairly good job so far enforcing this approach, in spite of some of the short-sighted bawwing I keep seeing.