The $19 billion acquisition that has finally woken the US up to the advent of mobile messaging is in part a defensive move. Facebook already has a big, successful messaging app: Facebook Messenger. But WhatsApp has more users in messaging, greater global spread, and more stickiness. 

More importantly, the age of social networking has transformed into the age of mobile messaging. No other app on the phone can demand the attention and repeat visits that a messaging app demands. In Asia, Africa, the Middle East, and Europe, these apps are more important than phone calls, more important than email, and more important than social networks. They soon will be in the US, too. Just look at what teens are doing.

I don’t think Facebook is stupid for paying $19B, roughly 10 percent of its market cap, for WhatsApp. Messaging apps represent a greater than 10 percent threat to Facebook’s business. But I don’t think the acquisition is going to deliver for Facebook what it hopes it might. That’s because the best messaging apps, at least in business terms, are not just messaging apps. They’re also platforms.

The fusion of Facebook and WhatsApp gives the latter a platform element and the former a stronger messaging element. But Facebook’s platform, what’s left of it, is not built around the one-to-one messaging experience.

There are certain elements fundamental to messaging that change platform dynamics completely. Just look at China’s WeChat, Japan’s Line, or Korea’s KakaoTalk. Games become more of a conversation between friends. Photo-sharing becomes more personalized and private. Brands deliver messages direct to phones through opt-in contact requests. The messaging app becomes a storefront. The thing that replaces your email becomes the thing you buy stuff with. As WeChat is proving by facilitating the sales of phones, fast food, and taxi rides, your messaging app can also be your wallet.

Neither Facebook nor WhatsApp are anywhere close to being able to manage payments in a serious, pervasive way. WeChat (and its parent company, Tencent) is way ahead of both Facebook and WhatsApp in that sense. And payments are crucial to the business of a mobile platform. This is one very clear area in which the US will have to learn from China.

WhatsApp timed its sale to Facebook to absolute perfection. Yes, it can claim staggering numbers. Yes, messaging is, beyond dispute, the killer app for mobile. And mobile, to get cute with the language, is the killer app for the internet. It is more global, more personalized, more constant, more flexible, and cheaper than anything seen in the first two decades of the internet. But WhatsApp is at the peak of its powers.

WhatsApp captured the upside of the first wave of mobile, but, without Facebook, what could it have done next? It is a pure messenger at a time when its competitors are becoming platforms. In fact, WeChat, Line, and KakaoTalk look more like enhanced versions of Facebook, reimagined for the mobile era, than what they started out as: enhanced SMS services.

For $19B, Facebook has bought a lot of user attention and neutered a potential threat to its social graph. What it hasn’t bought is the future of the consumer internet. That is being built elsewhere.