I guess my issue with Dark Designs is that the behavior debated about over the last 10 pages only makes sense.
If I'm designing this Fate why would I expect players to skip the 20 or so xp providing enemies just to get to the 5 or 6 enemies that are necessary to complete the fate? If I don't expect them defeated repeatedly, why would I set them to respawn in seconds?
I'm no game designer but its hard for me to imagine that if I were I would expect the following line of thinking from a rational adult: "Ok, I'm here to gain experience points. To complete this event I must literally run through a mob of enemies that provide experience points to attack a small number of enemies. I will, therefore, ignore the glaring opportunity gain a large amount of experience points by chaining/defeating enemies and skip them to reach the 5 enemies behind them."