In short, don't give someone a reason to do something. Just whine.
My experience does not bring me to the same conclusion as the article or your comment. I don’t think it’s about whining or an emotional appeal. Rather, I think it’s a matter of not giving the other party anything to argue with. If I enumerate the many reasons which have convinced me to not use Whatsapp, the other person has a lot of...”rhetorical surface” with which to attack. They may or may not be successful, but they can probably launch a decently cogent rebuttal.
On the other hand if I simply say, “I don’t like it”, and follow up with, “I don’t know, I just don’t”, there isn’t enough substance with which to find a logical flaw. Your friends might judge you for it but, in my experience, it won’t stick out enough in their memory for them to really focus on it one way or the other. They are sort of forced to concede because your reasons are inscrutable. Disengaging can be its own form of victory, because it forces a draw (so to speak).
Obviously that isn‘t persuasive; it’s defensive. Likewise, I used to compete in Speech & Debate tournaments at the national level. In that context you have to engage, by design. My team (and rivaling teams) had a philosophy that we’d impart to all new recruits: when you’re formulating your point, deliver it forthrightly and concisely. Support your position with the minimum that will suffice and provide further support as needed, to parry the rhetorical attacks you encounter. This gives your opponent less material to refute, which means each individual point you deliver is harder to detract. When you’re trying to persuade someone (especially if you have an audience) a reasonable point delivered confidently, and with one or two strong reasons or citations, is far more privileged than many “passing” reasons which can made the focus of a rebuttal.
Where I live, the exact opposite seems true. If you are an ardent user of social media, you are more likeley than not to be under a bit of scrutiny.
I'd argue that this is why the GP succeeds in their B/C tests - because they made it about their own choices. In A it's trying to convince the other party of a position on privacy instead which is, unsurprisingly, a lot harder
An appeal with facts, reasonable viewpoints and what not is effective if your audience is already heavily biased towards your viewpoint.
Appeals based on emotion and whining are likely to be called out by an audience that's inherently skeptical or believes very specific ideals surrounding the nature of discussion (the "debate to reach a higher truth, not to win" crowd).
Unfortunately, I've found what you said to be true with audiences who remain on the fence or don't really care about whatever issue is at hand.
Many posters here fall into the camp to whom discussion is an attempt to reach the truth so they fail to see the rhetorical forest for the trees.
That's not to say we don't have our blind-spots when it comes to emotional appeals, however. That's just human nature.
So why don't we all whine?
This I have asked of shouting. Normally I politely ask people to do things with a friendly tone of voice. However there have been moments, e.g. on-coming car catastrophe, where I have shouted at people and been surprised at how quickly people move or do as they are told. Shocked at being heard and being 'obeyed' I have wondered why I don't do it more often. I dismiss the idea as it is not me and contradicts many aspects of my upbringing. But you can see how it is that some people get what they want in the world by shouting/whining or being a general narcissist.
Having lived with a person who is hearing impaired, the effects of shouting on reflexive action will dissipate after the first week.