I think most of the criticism here is simply based on the overly broad use of the word "confidence." There is an interpersonal "professional" confidence, which

I think most of the criticism here is simply based on the overly broad use of the word "confidence." There is an interpersonal "professional" confidence, which is needed to function in the business world (although as many mention, you need to avoid arrogance so balance is needed). But the article is referring to a different kind of confidence: The belief that your work is automatically good. Nobody needs that kind of confidence, because no one's work is always correct the first time. Lacking the latter confidence can give you more of the former, as after you've double/triple checked your work you can confidently assert the quality of your work.