I think the point here is that your prof was criticising you rather than your output. That’s why it’s brutal, because it’s personal. He’s being honest about his feelings but it’s not very helpful to you. So I don’t think it’s fair.
He knew I was bullshitting and he knew I knew that. There's no point in telling me what I got wrong when I'm well aware of it. If I had put more effort into studying, I wouldn't have gotten my analysis wrong. Or if I had come in for help before turning the assignment in.
Bringing this back to the article - the context for candid feedback is a competent workforce. By your own admission it appears you we’re still in the process of learning about competence so the prof was not providing candid feedback of your submission but questioning your competence. That’s a different and necessarily more personal discussion!