"Texting is expensive and regional, and nobody uses email, wants to remember email addresses or IM handles, or deal with spam. WhatsApp totally fucked themselves by not running on tablets. For lots of people, the most effective way to reach them quickly is facebook messaging. That's fact, not opinion, and how intrusive or shitty facebook is totally irrelevant to that point. Not having a facebook account means that you are sabotaging your own communications effectiveness."
The people who'd do this are exactly those people I don't feel any need to communicate with. Is it work-related? E-mail and sometimes phone are given. Is it not work-related, but urgent? I still have a phone. Is that costly? Perhaps, but if you have six urgent things to communicate every day, perhaps you have a much worse problem than having to pay a lot of money. Is it anything else? Well, what could it be? I have no idea.
Frankly, this whole "you have to live a hectic social life, everyone's doing it!" movement puzzles me.