Many people don't use facebook. I thinks WhatsApp is a better example, it's even more ubiquitous, though I'm sure there are still people who don't use it. Heck, I'm personally thinking of stopping, it's just that everyone is there. Two of my recent orders were negotiated by WhatsApp. It's used almost universally.
I think that depends on what country you're in. The only people I know who are on whatsapp are immigrants who use it to talk to family in the old country.
