People only die because A) they have no method of communication and so can't be told information (where the question is more of a why do you have someone who can't communicate in the raid) or B) they aren't properly informed about the dangers and how to counter them. Heaven forbid I actually spend 5 minutes explaining a part of the raid before throwing them into a new section. And while I haven't beaten the raid on hard (mostly because I haven't found a group ready to give that much time and treat it any differently than normal raid), I have ran the normal raid six times in one day. And there is a big difference between the two. Normal raid can be carried by four people. Hard raid? Not so much.