> to even have a rheumatologist referral to begin with, some previous combination of [doctors] would have had to have suspected an autoimmune possibility and created some documentation to that effect

This is a good point. Even when a diagnosis is obvious, a doctor may not say it outright and instead make a referral to a specialist because it’s not their specialty to diagnose that condition. This is a good thing because they’re not that specialist so they could be wrong about it, and if they are right, then they should make that referral anyway - and end result is the same i.e. a referral.