Storyline missions need to save your progress
Content Designer
Checkpoints are very different from saving/restoring a quest that’s in progress. Checkpoints are really just resurrect points, but trying to restore a mission “in progress” means saving the state of all of the monters, enemies, quest steps, etc. There’s a lot of behind-the-scenes scripting that goes on quests, and trying to save/restore the state in a way that wouldn’t introduce new bugs is extremely difficult, at least in an MMO that isn’t set up to “save” stuff like a single player game might be.