This is true.
I just thought of another reason that I lean towards B (although since I've never had to live with that, I'm well aware I could be talking nonsense). It's easier not only for strangers to get, but for you to get. Mental illness diagnoses are still so nebulous and changeable, hard to wrap your head around. And the illness itself can surprise you all the time. With a physical thing, maybe the pain would come and go in ways that would also surprise you, but at least you would understand the nature and source of the pain.