I don’t mind SOLO content in WOW but the DUNGEONS and RAIDS are not for that
its group effort and group content
Mage tower was perfect example of SOLO content
if you really like solo go and spam blizzard with adding stuff like mage tower 
You are trying so hard to blame it on some bad design when in reality you are just BAD or you were so unlucky to play with bad players.
Let’s be real here the mechanics of last boss are easy
Comet storm is the easiet one to counter just slowly go back in circle 
Oh yeah, I’m bad because the boss reset itself.
What i can see here is that your group died to mechanics and as such you wiped because this boss wants at least 2 of you alive. The wipe criteria is just different
Your group died to comet storm. Wasnt you necessarily who was bad, but your group was.
If I can… why not? 
It’s a challenge. Even Blizzard hid a mount under a solo dungeon 
EDIT: 
Try now to convince me dungeons are not solo content
Didn’t go too well even with 4 people alive. People died. Because I as the healer got dark exile. We still killed him but I’ve wiped to him in higher keys because of me getting the dark exile as a healer even though others are alive.
I mean, you just have to move on comet storm… and dispel the roots when no ones in the aoe.
Except none of that was the problem.
Dark exile resets the boss fight when you are the last one standing.
Oh, so your team died by not moving…
And the boss tried to reset.
Gotcha!
I thought you were saying comet storm was the issue, which it kinda was. But I see your point 
How these things usually works it it picks one out of 3 players and prioritizes DPS first and tanks last, meaning that if 1 dps is dead, it’ll be one of the 2 remaining DPS and the healer
In general when you leave a bosses assigned combat area the boss resets, some bosses move some characters outside of the combat area to deal with a mechanic
If everyone else is dead and there is just one character alive in such a situation, they get moved out of the combat area to deal with the mechanic, this however means that the boss has nothing to fight in the combat area and resets
These kind of mechanics have always worked like this in nearly every if not every iteration in which they exist
tl;dr
try not to die
That screenshot is over a month old and as such not relevant to your above group.
The screenshot should be a bug yes. That you as the sole person get yeeted down with dark exile should not as its common practice with mechanics if not enough people are present.
I don’t even get thrown down on Xav. As far as I’m aware, I’ve never received overgrowth on me in mists either when I’ve been the last one standing as a tank but that might be because they’ve died before they can cast it on me. Can’t recall seeing volatile acid go on me either.
It also happens when you’re the last DPS alive, or your group wipes while you’re downstairs. I don’t see this as a problem tbh. I do want these things to get fixed for the next expac though, so you can actually solo mount runs 
Xav just skips throwing you down when you are the last standing player against him.
I like this boss. It doesn’t really get harder at higher key levels because everything is a one shot 
It’s both actually.
Why is dark exile a thing for tank anyways?
Is not unless the tank is last one alive.
Most of bosses with similar mechanics work same way.
Explain this.
4 people alive. I get targeted as a healer.
That was a bug and people already told you that, why you still hit on the same buttom.
The fact you get exiled as a tank when none is alive is not a bug.
The only other boss in SL dungeons that moves you out of the combat area with his abilities is Xav and he straight up skips that when you’re standing alone vs him.
It’s happened several times, it’s not a one-off thing. I’ve wiped due to it on my druid. I’ve seen it happen on streams as well. It seems to be intended behaviour since reporting it has done exactly nothing.