I'm genuinely fine sharing my medical history, but I don't know if my lack of shame about e.g. testicular torsion, or the way that I lost my notes for a bit and unnecessarily got repeats of vaccines I'd already had, are a sign of being in possession of a boring medical history, or an indication of an uncommonly diminished shame response.

Whatever it is, I am aware that my lack of concern here is something which makes me different from normal people. I don't really get why people in general are ashamed of their medical histories, but I nevertheless absolutely do support everyone's right to keep such secrets, because there's a few specific cases where the medical history reveals something socially damaging either in the present or with a risk of it becoming so in the future, the obvious example of which is an abortion given the US seems to be facing a loss of freedom in this regard.

(Perhaps most people have something socially damaging in their medical histories, and I've just not noticed because nobody says the thing?)

This is not honestly engaging with GP's statement.

The benefit only accrues if the sharing is universal.

I am too private a person to agree with GP, but it does seem that most health issues that are visible to the passerby or casual acquaintence are less stigmatized than the ones that can be hidden. There might be something to the idea.

Of course you'd have to agree that de-stigmatizing is more socially important than privacy. I guess I'm privileged enough to have no stigmas, secret or otherwise, that I consider more important than my privacy. But I know others are less fortunate.