Getting "party defeated" even if not everyone is dead?

you lost because the hero did not have a ressurect skill What he said. You were kicked because if a hero does not have a ressurect skill what good is it? You'll stay dead doing nothing with a useless hero with no ressurect flagged back. The way I see it, you would have had to /resign even if the game didn't kick you out.

I know you get kicked at 60% DP but why the hell would it kick me when I still have 1 hero alive, flagged very far as to make sure he doesn't die (so I can keep going).

It's ridiculous, I cleared the entire area (~250 enemies) except one boss which got me to 60% so to make sure I didn't have to redo the area I flagged a hero without a ressurection spell back. But nope, even though he was still alive, "party was defeated".

F...ing bulls..., my hero was still alive and if I had know ANet would screw me I would of just bought morale boost by using /kneel. Its pretty unfair to kick a party even when they still have members alive. it's just the way it works dude. 60dp in HM: whole team is wiped out + one last hero/hench standing without rez = game over

Just try killing the harder mobs or bosses first next time you vanquish. And bring a resurrect skill on the hero if you want to safeguard in this fashion. No rez is why you were "defeated." If you kill the tough bosses first you don't have to waste your time with doing everything and then getting wiped because of DP that was built up while vanquishing other parts of the map.

It does suck, but unless that hero was built to solo that boss... I don't really think you can complain.