Why do so many people believe that alternative medicine can cure practically any disease?

Here’s one counterexample (and there are others):

Only traditional medicine can save the life of a type 1 diabetic. Do you agree? None of the alternative medicines can provide a substitute. Will fans of alternative medicine accept that? Sometimes I’m not so sure. Islet cell transplants are being investigated and the use of stem cells to produce a new population of functioning beta cells. But that too would be a traditional medicinal approach of conventional medicine.

In my opinion this still means that we should take alternative medicine seriously. In some cases it can be very valuable. Not every illness requires strong pills or surgery. What is your opinion?