No, WhatsApp won because it successfully replicated and replaced the SMS experience in the developing world, where the cost of data was dirt cheap in comparison to the cost of a single SMS message.
>>linuxd+(OP)
Experience on WhatsApp, Telegram or any other IM is vastly better than SMS. Unless by SMS you mean iMessage - then it's even simpler - most of the world doesn't use iPhones.
Given the choice between SMS and a service that provides the same functionality is free, superior in most ways, borderless, etc. the choice to use whatsapp is obvious.
>>linuxd+(OP)
Mxit existed long before WhatsApp. Possibly a decade. I used it in the developing world and it wasn't anywhere nearly as successful as WhatsApp. For example, nobody in my family used it.