I'll just mention this, even with your cynical retort to the suggestion, FC is group of people moderated. You're less likely to find jerks in an FC since they would be kicked out. Find one that fits you, and you'll less likely run into people who don't fit your play style.
I had a same experience as a WHM for this battle.
Also being new to the Trial and jumping onto a DF of Battle at Big Keep.
- DF starts and the Full Party logo flashes across the screen and I announce my greetings.
- I see some chat greetings replies, and immediately announce I'm new to the fight, and ask for any particular mechanics.
- A player explains at the last stage that a healer is going to be picked at random, and that the plan is to sacrifice the healer to focus on a full DPS burn.
- I was randomly picked by the Boss RNG to be the sacrifice, I died.
- I was raised, and RNG picked me again, and died again. This time boss dies.
Entire fight ended without anyone needing to waste efforts in breaking me out of the chain jail. Was it rather a boring fight to heal? Yeah, I did was play the sacrifice role, but I did my job and bought time for the DPS to do theirs.
I don't see anything in this instance that Elmeron should have taken personally here. Players were just going through the motions of completing the fight, Battle at Big Keep, and Elmeron happened to become the healer sacrifice here.
No players were actively persecuting him, from the account of Gurpsmeister.
The group's battle strategy might not have been explained, which Elmeron had insecurity from the possible chat silence took it personally;
The only thing that might be questionable is whoever decided to start the fight while people were still not inside the battle field, especially if it can't be won without main healers.
This is bound to happen occasionally with any public DF groups.
E.G. People locking out entire parties at the Atomos fight of Crystal Tower.
SE can fix this by adding a lock to any mid-boss fights preventing players to start the battle until everyone is inside.
But imagine one AFK player in CT locking out everyone from progression because he isn't ready to play, and then everyone has to either wait, or vote kick the AFK, or even worst wait for the vote kick timer.