Missing the point
Sounds like this struck a nerve with you. But I think maybe you are missing the point. The point of this article is how to quit your job with the least amount of detriment to your reputation as possible. All items except for #4 (asking for reference) are all about maintaining a good reputation as being a professional.
As far as the employer being required to give notice of termination, that depends on where you are. In Texas there is no requirement (for either party) of notice or reason. I am not required to give notice, but I would never consider quitting without doing so. Not because I have to, but because I want to maintain my hard earned professional reputation. Also keep in mind some company policies require the two week notice if you are to leave with full benefits. For instance if I don't give two weeks notice I cannot take my unused vacation time.
Is this fair? Nope, but it is the world we live in.