By replacing the word hybrid with Shadow Priests everything would make more sense.
These changes still do not address the issues with Shadow Priests, so many people are sitting here wondering why the hell would they implement them. Shadow Priests healing is OP mainly because:
1) They have a vast variety of healing spells or types (renew, PoM, PW:S, and flash heal)
2) They have ridiculous scaling of their heals (even before PvP Power gets added in)
3) Their heals are a separate school from their damage spells allowing them to heal or DPS when they get locked out of 1 school.
Add in Shadow Priests insane CC/control, good survivability (with many cd's less than a minute), and good damage; you get why shadow is OP.
On another note, pures have insane healing nowadays as well. The main difference is that pures can only heal themselves as opposed to hybrids healing anyone.