Whenever somebody has to send me something, the first thing I'm asked is my WhatsApp number. I simply say that I don't have one and suggest them to send me an e-mail instead. Some people accept that, but most start lecturing on the importance and convenience of WhatsApp.
Before going further, I'd like to put it straightforward: I'm not against social media in general. It is all about some particular services.
I have multiple reasons not to use WhatsApp or Facebook -- both technical and ethical. I'd like to list them all on this website someday, not now because it will be a time-consuming process.
What I'm trying to focus on today is not an issue with WhatsApp, but a situation caused by WhatsApp users (or users of any similar restricted chat application). When somebody says something like I'll WhatsApp that pic, he is essentially forcing somebody else to use the same service. This is where the freedom of choice gets threatened. When I ask somebody to send me an e-mail instead of a WhatsApp message, I might be forcing him to use e-mail. But I'm not forcing him to to use any particular e-mail service. He has the freedom to choose from hundreds of free and paid services, or he can even opt to run his own mail server. Yes, I'm forcing him to use some e-mail service, but it is not as bad as imposing a particular service.
This is why I'm against communities, especially in work places, choosing WhatsApp as their primary way of online communication. For example, I know school teachers in Kerala who are forced to use WhatsApp because their colleagues and even superior officers share important documents via that particular service. In such cases, WhatsApp is a psychological virus. But if they were using e-mail instead, there would be freedom of choice.
And about convenience. I simply don't understand how sending an e-mail becomes inconvinient for a person who already has a smartphone and Internet connection to use WhatsApp. It is much simpler actually.