Your education, your language and your intelligence are not private. Your medical records are, and depending on where you live the exposure of your medical history can be dangerous to your life or freedom. So no. Not nearly the same, much less worse.

Do you use an AI when writing or commenting on HN?

You don't need AI to write as someone else.

On the Internet no one knows you're a dog.

Do you write things that you intend other people read?

The value in that writing, one would assume, would include your education, culture, and intelligence.

False dichotomy. Medical records and writing style reveal different categories of information. Medical data: extremely sensitive, can enable discrimination/blackmail. Writing quirks: revealing but not dangerous in isolation.

The real question: who has access and what can they do with it? Using a local open-source model to polish your writing is fundamentally different from sending everything to a corporate server. Context matters more than the tool.