>I recall multiple cases of formal/semi-formal interventions where other professors or the department had to force an advisor to let the person graduate (they wanted to keep milking them for more papers).

That's kind of what I mean though. In grad school other professors you've worked with might still keep an eye out for you. Under an exploitative employer, the way I was previously, I wouldn't know any better, I had no sense for the value of my time/work and I used to panic about having to send simple emails to people, quitting a job used to sound equivalent to suicide.

For me there's also the factor that as an international student, it's a lot easier for employers to exploit me than a school.

Edit: Although, come to think of it, I do know of other departments at my uni where even other professors can't be relied on to help in such cases. So I guess you're right.