I was in obsidian scar yesterday (public dungeon in rivenspire) and I was grouped up with a guy going for the achievements. He kept saying he needed the last hit on some mobs and I didn't understand until he explained it to me. Apparently, to get credit for a boss kill you need to get the killing blow.
This seems like the antithesis of the point of a public dungeon and is completely different then the entire rest of the game. Everyone always gets credit regardless of whether or not they did the most damage, first blow, killing blow or whatever.
Is this intentional? If so, why?