As a powerhouse Healer WHM can use it's healing abilities more frequently as it's gimmick. This gimmick shines in terrible situations. If your tank is under geared and your dps think red areas are for an experience boost than the lillies suddenly do a lot and help out in every single pull in a dungeon. The play style "benefits" tremendously from lillies but its a class tuned for learning and progression while Scholar and Astro are tuned for high skill parties and speed skills. All Healers can clear all content but they clearly have different purposes in their design.