A number of other responses are suggesting that the explanation is all about the switch to mobile. I'd argue it was less about the platform transition itself an

A number of other responses are suggesting that the explanation is all about the switch to mobile. I'd argue it was less about the platform transition itself and more that people misjudged what behavior that transition would enable. People generally thought the future was voice and video and text was of the past. Few people thought that one of the smartpjone's most powerful features would be a semi-decent typing experience. When I think back to 2008, sure, geeks used irc, but for most people the thought of typing messages in a chat room seemed hopelessly anachronistic. It wasn't something you do on your fancy new iPhone. Siri, released in 2011, seems driven in part by this perspective, and a vision that the future will be voice-based. The fact that a lot of people actually prefer texting kinda took the tech industry by surprise. People thought the more advanced technology that more accurately reproduced a conversation with another person would dominate. It turns out that the more psychologically comfortable technogy won, which I think is often the case. Of course, there are a lot of other reasons why apps like WhatsApp and WeChat have succeeded in developing markets that more driven by local infrastructure and economics.