User blog comment:Madman97/You know what really grinds my Wabbajack's? S3E1: I can't kill these guys/@comment-25109952-20131025182427/@comment-1600847-20131026152510

As I just said, if you make quest-essential characters killable and have radiant AI, then they drop like flies and the game becomes un-completable. I know a lot of people believe Bethesda made quest-essential characters un-killable as part of the "CASUAL GAMER CONSPIRACY!!!1!!!" but that's not the case. Without it, radiant AI wouldn't work.

I'd rather have some un-killable characters than show up to do a questline and find it un-completable because one of the characters died in a random event I had no power to stop because I was one the other side of the map. That is unbelievably frustrating.