Nowadays, seeking abortion/family planning could -literally- result in being jailed, and forced to give birth.
Mental health is a big deal. For better or for worse, if your employer/licensing org is aware of any mental health issues, then they could adjust how they treat you.
Crappy bosses could use your history as a way to discredit or manipulate you. That's exactly what the CIA does, whenever someone blows a whistle on them.
Some medical conditions can be interpreted by different people, in intensely negative ways. For example, at one time, being left-handed, meant that you were possessed by the devil.
Often sexual orientation/behavior is a part of your medical history.
But I'm suuuuure that no one would ever use this information in a questionable way.
Look at the "mug shot protection racket" sites. These sites leverage personal information that has been made public, as a way to force you to pay them to remove it (and then immediately republish it in another venue).
I guarantee that a number of folks on this very site, run those sites, and sincerely believe there's nothing wrong with it.
No. Just because "I have nothing to hide," does not mean that I get to force others to divulge intensely personal stuff.
In some jurisdictions, this not always the case. One example is the "Good Samaritan" law in California[0] which provides some protection patients seeking medical treatment for an overdose.
some are illegal - think threating drug overdose