The physical theories of electromagnetic fields contain some of humankind's deepest insights into the structure of the world. We benefit every day from the practical products of these theoretical investigations. It isn't that electromagnetic fields are irrelevant. There just aren't any miracles to be found. No, it isn't absurd.
Magnetic fields exist and do interact with the constituents of human tissues.
Magnetic therapy is condemned as quackery by many doctors. There are two principle reasons that magnetic therapy lives in the realm of quack medicine. Unsubstantiated claims are made for efficacy. The quasi-religious motivations that lead people to try this sort of therapy. This generally manifests itself as bogus claims about aligning or re-energizing your personal energy field.