For some positivity, I ran the Twilling with two friends on discord and we had an DF AST as our healer. I asked them if they wanted to do big pulls, they said "If you want to, I've only done this once". I respond with "I have faith" and we start with the first pull and gradually work our way down. Everything is going great, I'm using my normal cd's proper AST is healing fine, dps are aoeing all over.
Boss is handled fine (minus the few deaths we had as my friends were first timers), then we get to the next mob. Handled it just fine but the pull after I dun goofed up. I pulled immediately after and I'm still getting used to the CD time of Arm's Length (as it applies a slow effect on hit which helps for healing), so I misjudged it going the full way. We kill about 4 of them before I died (a second before popping superbolide) and we end up wiping.
The AST says "I'm sorry I couldn't heal to match that much damage you were taking" and I apologized saying "No no, it was my fault for not managing my CD's proper. I haven't done this pull with too many healers so I apologize."
Me and AST just start talking and they discuss how the first time they ran this dungeon the tank pulled wall to wall using 0 CD's causing multiple wipes. That when they got to the second boss they did a vote kick just to get that tank out of there to replace it with one that would actually tank proper. They thanked me for using my cd's on both mob pulls and boss fights and while I was grateful they said that I don't think it needed any real thanks when it's just our job. Rest of the dungeon went totally fine after with me doing the big pulls normally after the second boss including those awesome kettles with the donut aoes. I love stunning one to get safely under another's donut. Last boss as well with two new timers did lead to some deaths but we never wiped and everyone had a good time.
I'm sorry for any healers of the current content that are dealing with tanks not using CD's or doing the absolute bare minimum for mitigation. My heart goes out to you and I'll be joining you soon when I lvl my WHM.