That's a legitimate question, and I don't pretend to have an answer. I believe God has healed in numerous cases that defy explanation by placebo, misdiagnosis,

That's a legitimate question, and I don't pretend to have an answer. I believe God has healed in numerous cases that defy explanation by placebo, misdiagnosis, or other means, but that tells me little about why he has not done so in others. I could come up with theological theories, but none, at least presently, that I would expect others to find satisfactory. It is also, I admit, not a question I have specifically spent much time considering or investigating, - - though I acknowledge its difficult implication.