I suppose they do it because it catches attention. A slap in the face catches attention too. For me the two work similarly. (At least I think they do; I can't remember being slapped in the face.)
Usually I just grin and bear it and feel like a schmuck for giving them their damn pageview, but this case is interesting. It's not only rude, it's incongruent in a post that ostensibly is about how to treat people decently. Evidently the author's highly developed empathy doesn't extend to his readers. Once you see that, the whole post appears coated in a thin slime of managerial manipulativeness.