It went away with modern medical ethics. A doctor is ethically required to prescribe medicine which he or she honestly believes will address the problem, and tell the patient why that is. It's about informed consent. If a medical doctor prescribed a homeopathic remedy, how do you imagine the conversation going?

"Well, the remedy I'm giving you has no active ingredient--it's actually diluted so far down that it's just water! Nevertheless, I think it will reduce your pain/swelling/etc because of the placebo effect. Which requires that you think this is a real medicine--oops."

This is the same reason that doctors are now taught that sugar pills and other placebos are ethical only in medical trials, in which the priority is the testing of a treatment rather than the actual treatment. Using placebos in place of tested treatments in actual practice is equivalent to lying to the patient.

I'm glad acupuncture helps you feel better. However: do you know why your back is hurting? Have you had a doctor actually look at your back to make sure the symptom isn't a symptom of a real, serious condition? Or do you just trust your "personal experience" which says that acupuncture makes pain go away?

The real danger of alternative medicine isn't that it doesn't work, but that it makes people less likely to look deeper into their problems. In your case and most others, it probably doesn't matter, but from time to time you really do need that "proven" treatment.