There is no such line. The actual line is whether someone is newsworthy; the safeguard you have against journalism abusing random people (which it has done, often, over the last 150 years) is that journalists ordinarily don't write intrusive stories about random people.

(There are some other safeguards, but they're highly situational.)

The conflict between journalism and "doxxing" is a Redditism that people are frantically trying to import into real life. Maybe Reddit norms will upend the longstanding norms (and purpose) of journalism! But nobody should kid themselves that the norms have always been compatible.