See, and in my case, the only reason I built up enough confidence to get into Extremes and Savages was that the game was casual and friendly. In 10 years in WoW, I have never dared to enter any high end content, because people were toxic even in low level normal dungeons if you god forbid wanted to do the whole dungeon for quests.
Casual appeal is the best way to get people to eventually try hardcore PvE content. The transition happens gradually, naturally, and there's no pressure like in WoW, which doesn't have anything meaningful to offer to players who don't enjoy WoW endgame.