_{[He saw that. Note to self: this is not Melvin, whom you can natter with and argue about quantum physics for hours. Do not jabber with Jim.]}

It isn't that healers are incompetent. It's that anyone will seem incompetent the first time that they are presented with a challenge. In the field of healing, like the muggle field of medicine, it's possible that people may die in the time that it takes for the healers or doctors to determine the best course of treatment for a particular injury or malady. I happened to get particularly lucky last term

This has been true for both the wizarding world and the muggles, throughout history. It is a simple fact of science that sometimes, trial and error must be resorted to and, in the bodily sciences, the "error" occasionally costs lives.