Obvious comments are great for code reviews because it's a validation that what you intended to do is what your code actually does.
From the article, the comment about adding a vertical scroll bar allows me to review the code and to check that it does indeed add a vertical scroll bar and not something else.
Did the developer intend to require password lengths of at least 8 characters? A simple comment would tell me what the developer wanted to do and then I can verify that it was done correctly.