Therapeutic massage is expensive but popular and pleasant, with obvious subjective value, and proven benefit for anxiety and depression … but no other clear biological or medical effects. Most notably, the evidence that massage can help back and neck pain is sketchy, and there is no reason to believe that massage can help much with any other common musculoskeletal pain problem.
Training and certification standards for massage therapists are all over the map, and most practitioners have barely scratched the surface of musculoskeletal medicine. The profession is rife with pseudoscience like crank theories about the causes of pain, the myth that massage detoxifies, or that painfully “deep tissue” massage is needed to “release” tissues (which is stressful or even harmful for many patients).
And yet some medical benefits are plausible despite the lack of evidence. For instance, many apparently successful treatments may be due to the effects of pressure on “muscle knots,” which are a likely factor in many common pain problems, but poorly understood (and difficult to treat). And regardless, the effects on mood and mental health are so profound that patients can’t really lose — it’s a valuable service whether it “works” for pain or not.