There's a huge benefit to getting a specific diagnosis. Treatments for Lupus vs. MS vs. vasculitis vs. other AI diseases are very different. And many of these are life-threatening without proper treatment; lifestyle changes won't cut it.
My wife struggled with weird autoimmune symptoms that eventually progressed enough to get a diagnosis. At the time of her diagnosis, her life expectancy without treatment was 1-2 years. I empathize a lot with patients and doctors who are trying to dial-in on a mysterious illness.
Yes, agree on the benefit of a specific diagnosis, but those aren't available to everyone with autoimmune symptoms. As mentioned, there are people who check all the boxes but are short one or two to get a specific diagnosis.
In these cases, the psychological toll is pretty heavy - the uncertainty of your future while your very identity is being challenged. I've seen people respond badly - instances where people engage in a tragically comic route of turning to chronic alcohol intake, becoming inactive/sedentary, bandaging emotional pain with bad diet, etc. Precisely activities that are known to aggravate autoimmune disorders. This is a horrible reaction.
Now, even with a specific diagnosis, the first thing your rheumatologist is going to tell you is that you need to make lifestyle changes - diet, sleep quality, stress levels, etc. That's going to be solid medical advice regardless of what drugs you go on.
For those without a specific diagnosis, adopting these lifestyle changes is still good advice and within reach. There is no instance I've seen where someone with an autoimmune disorder can rely solely on drugs and be otherwise "normal". The drugs (especially those beyond hydroxychloroquine) have unpleasant side effects of their own that need to be managed. In all cases with drugs, the goal is to get the disease itself into a managed state, and ideally into remission. That's not possible for everyone, but for plenty of people it is possible to manage mild instances of disease without drugs, and enough of a possibility that I think it's at least worth a try. This doesn't mean stopping your drugs and doing reckless experiments, but in consultation with a rheumatologist weaning off drugs while having adopted lifestyle changes that avoid known triggers for flare ups. If it doesn't work, go back on the drugs.
My wife struggled with weird autoimmune symptoms that eventually progressed enough to get a diagnosis. At the time of her diagnosis, her life expectancy without treatment was 1-2 years. I empathize a lot with patients and doctors who are trying to dial-in on a mysterious illness.