Which classes was it? My brother used to play a sorc and neco, he didnt have any problems in hardcore. They didnt remove Iron Maiden from players, just mobs.
I remember running with my friend in one of those portals in ACT 5 in hell, mobs werent even in the screen, yet they managed to put Iron Maiden on us killing us both (thats before they removed it).
Examples->Something like brutal would mean mobs/bosses doing high ammount of dmg compared to your hp leaving you dead in 1 or 2 hits (Death lords *Mintours with dual Oo for example*), something unfair would be completely neglecting your build by having an immune against it.