Yeah, it's known that auto-immune diseases are difficult to get diagnosed right or diagnosed at all. It took 7 years from the first hospitalization for me to get sarcoid diagnosed. Celiac was one of the things tried along the way. Dropping wheat gluten did nothing for me.
The MP is claiming a lot in terms of the various diagnoses it might address. However, all of them are also treated by the same set of corticosteroids, so this would not be the first thing to treat auto-immune disease as group.
The doctors describe sarcoid as 'a systemic disease of unknown origin'. The ones I saw pre-MP seemed to understand this as meaning sarcoid can attack any organ or system in the body, which makes it hard to diagnose as it can present almost any symptom in the medical lexicon. From my own experience, and talking to other sarcoid patients, it's clear that sarcoid is a systemic and progressive disease and it will eventually attack every system and organ in the body. Starting with high fevers and IBS symptoms, the sarcoid progressed to diabetes, thyroid symptoms, and retinopathy. It's not unknown for fibromyalgia to blossom into lupus, or lupus to become sarcoid. All of my sarcoid symptoms are gone or receding.
Once understood as a set of pathogens that use a shared trick to evade the immune system, it's understandable that a single approach (though with wide spectrum antibiotics) can cure a bunch of symptoms masquerading as separate diseases.
That's progress.