Having had arthritis since my teens, I have tried a number of 'alternative' remedies/relievers. None worked, so I continue the take painkillers daily. They help enormously and always have. Since I've been taking them for nearly four decades now without any noticeable side effects except the desired one (pain relief), I do wonder why people are so averse to taking them. Perhaps I have just been lucky with no side effects.
I don't think GPs can be blamed for not knowing a cure for arthritis. Nobody knows. Besides, it isn't one disease; there are at least two hundred variations. That's why money is needed for research. Bit by bit more is discovered about causes and how to prevent problems. Other chronic illnesses are the same. There often is no cure — perhaps may never be — but that isn't anyone's fault, just unfortunate.
As an example, after decades of advice about change of diet to prevent heart disease, the rate of of heart disease has not changed. People who have it tend to live longer because of better treatment, but the incidence of the disease has not fallen. The logical conclusion comes in two parts to my brain: the advice is incorrect so far (or at least incomplete) and there is no known reliable cure, only relief.
Use any relief you can get is my approach, but don't go blaming people or being cynical about medical research.