I agree ScH is left behind, but I'd say all healers are good at healing, with AST being the one that's superb at it. WhM lacks shields and both ScH and WhM pay dps taxes to heal and have to turn to GcD's much sooner than AST.
The meta is AST+other healer and ScH's issue is it has inferior damage and doesn't bring extra healing to the table that AST can't cover or needs. In addition, WhM is straightforward and effective and ScH has a clunky pet that ghosts and delays, dissipation and Place to manage, and requires better fight mapping due to weak GcD's if you waste resources.
WhM hits harder and does the same thing with far more ease and AST does everything better. ScH has been on a steady decline since 5.3 and is close to taking the least popular heal spot from AST now.
