It is all about when you get killed and there is no other way you can rejoin your team mates.
Especially in the last boss fight when if you get killed they put you up there in the “balcony” and you are completely useless for your team.
You just stay there and watch the other(s) doing all the work. The only solution is for all party members to get killed to start again from a checkpoint but this is an awful mechanic. Sometimes you cant even get killed because the NPCs heal you.
So you have a scaled up Mordemoth to fight with less and less players.
I hope this mechanic will go away in the next expansion if its not fixed in here also because is very unfriendly.