The expectation of privacy came from the fact that this is a recruiting platform; even mediocre recruiters know that discretion and privacy are critical since leaks about job searches can get people fired.

You’re right. Supposedly the hints have been in the privacy policy since December 2019.

Identifiers, third parties. “ Companies that use our services to be matched with job candidates. Candidate profiles created by our users are accessible to the public. “

https://triplebyte.com/privacy

Naive optimism.

There was never any indication our involvement with the company was going to be made completely public.

Others would have similar expectations, from other online services. We expect them to use our data in very limited ways that they've specified, and not suddenly start disseminating it in unexpected ways (if that is indeed what's happening with Triplebyte.)