WAR healing with Tetra, Lustrate, and Essential Dignity isn't really a problem of their class, but how SE has chosen to categorize them. It leads to problems with more than just Defiance, because while Cure/Physick/Benefic/Medica/Helios, etc., are all healing magic, Tetra/Lustrate/ED/Benediction are "abilities". I'm not sure if that is how they intended them to work, but it's been a big concern for healers because they are also unaffected by things like Fey Illumination.