At this point, it doesn't matter what their intent is.

The game is objectively not designed to have one (1) healer use all of their healing tools in content let alone 2.

That needs to be fix. Period. That the devs refuse to do so is their own folly. Look at how you design battle content and make healers match it. Because they don't. Its been two expansions. Your vision for healers HAVE FAILED.