"Doubtless"? Where is the proof? They are asking people to stake their lives on something that they cannot prove.
Besides, knowing what kind of a God Jehovah is, He will promise to take care of the dirty work, and then expect people to do it under threat of joining the dead if they don't maintain a speedy pace. And no wishing any of them would have survived--sentimentality is a dyable offense in the New Dark Ages.