You probably mean Mxit back in the days!

I can't speak for the rest of the world, but in South Africa basically everyone uses WhatsApp, because SMS isn't free and most contracts don't include unlimited SMS's. Whatsapp just made sense. There's a few of us that switched to Telegram when the whole WhatsApp privacy policy conundrum came up a while ago, but most people still use WhatsApp as their main form of communication in SA. Even the Telegram guys mostly still have WhatsApp.