There is a spectrum of healing that most people do not understand. And every form of healing works to some degree within that spectrum. Some forms of healing work across more of the spectrum than others.
This spectrum does not look like a rainbow but it has some similarities. Like as in a rainbow where if you you removed a color or two, the rainbow fails to persist with the grandeur it would of with the full spectrum. The same goes with healing, if one part of the healing spectrum is missing, full long lasting healing is nearly impossible to accomplish.