It's not an exploit (and I don't know how anyone got to that conclusion) however it is an unbalanced Fate and should obviously be nerfed or redesigned. Fates are about public cooperation and the way that this Fate is designed, is so that private parties benefit from the public quest and the public who is not invited to the party or parties just happen to be full, cannot get the benefit from the Fate. As soon as your average player cannot benefit doing a public quest, it's becomes a poorly designed/thought out Fate and it is not in-line with the design of the game's Fate encounters.