Unkillable healers

[Zojha]

MCH and BRD burst (while one is notably quicker and easier than the other) would be more than enough to delete any healer, but you'd basically have to do it together.

Well, you have 2 seconds of Barrel overload stun to deal 14000 damage, after that the OGCD heals come in (which can't be silenced).

Barrage/Pitch Perfect is 2k. Empyreal Arrow 1k. Sidewinder 1,5k. Dots 750. Straight Shot 1k. Total Damage you can do in that time: 6250.
MCH... roundabout math: Overload 1k, BTE 3k, Heated Clean Shot 1,75k. Let's say two GCDs due to pre-load and put it at 7000. With Troubadour and Overheat buffs and absolutely perfect coordination and setup and the healer not using a shield/defense buff or concentration beforehand, nor using Purify to get out earlier, that could work, provided the healer doesn't have a tank helping him that is capable of just as much coordination.

I wouldn't say it's "more than enough", though. You just barely make it.

As for the topic, in general, well... they don't even attempt to balance healers and pretty much admitted to it in a roundabout way. They instead purposely (over)tune them to make them more popular, likely in another attempt to salvage their "premium" mode Feast, which has been plagued with a lack of healers since the dawn of time.

It's unlikely to change anytime soon, so far most of their decisions (Astragalos aside) actually seem to go into the opposite direction, so I'd say: Don't like it? Don't play it. The devs have no intention to balance power, they want a balanced population.