Going to reference #FFXIVHealerStrike here, given the fact that it is ongoing, but wanted to highlight for everyone on the forums to see.
Self-sustain outside of Healers is breaking the Trinity. If it is not addressed, then you may as well have thrown 4 Jobs into the trash.
And yes, I know WAR is the biggest problem here: but for those who don't know what the Trinity System is, The Trinity System essentially is a game system that consists of three 'roles' or 'classes' or things that work together to create a balance for the game's content. When one of those roles skews more into another role? It starts to create imbalance.
Think of a Triangle. You want the Triangle to be a perfect triangle, ideally - that way you can keep everyone happy. Tanks are the Blue Corner of the Triangle, DPS are Red Corner, and Healers are the Green Corner.
Right now, this triangle is heavily slanted to the point it's a line. The only thing you see? A very tiny sliver of that triangle, while the Red and Blue Corners are stretched out to their extremes. That shows the state the game is in right now.
Here's a visual.
Corners B and C are Tanks and DPS. Meanwhile, Corner A is Healers. See how stretched out B and C are? That's because they've been getting more things that make them self-sustainable and allow them to simply take a 3rd DPS. If A is rendered unneeded, then B and C will simply take their place because they're faster - if not more efficient than Healers in terms of recovering HP. When a role loses depth, they start to become irrelevant in all types of content that isn't hard requiring a Healer to be there.
As shown in Endwalker, Dungeons are clearable with Tanks and 3 DPS. Savage and EX was clearable with Tanks and DPS. Ultimates were cleared with Tanks and DPS.
So, what does this have to say about content? Either the jobs themselves are overreaching their role, or the content's damage output is too low for healers to be required, not accounting for all types of avoidable damage.
If either of these statements you say 'yes' to, then you agree with the image shown: That the Trinity is broken in such a way that you might as well not have one going into Dawntrail.