Dec 20, 2013 · 4 minutes

The last year has been very active for WhatsApp. The world’s leading messaging app has continued to see explosive growth, and is now seeing 400 million active monthly users – an important metric that shows people are not only downloading the service, but also actually using it. This dizzying milestone is the cap of a busy 12 months or so in which it was rumored to be the subject of big-money acquisitions by first Facebook and then Google, and in which previously quiet CEO Jan Koum came out of his shell for on-stage appearances, pointing out that WhatsApp has more users than Twitter.

In announcing 400 million active users, Koum was again uncharacteristically vocal yesterday. “We want to steer the conversation to be about active users, not registered users,” he said, according to AllThingsD. “We’re a bit fed up and frustrated about people talking about registered users. We think it’s important for us as a leader in the space to speak up and be ethical.”

The comments were a clear swipe at competitors such as Line and Kik, which have also been trumpeting seemingly impressive registered user numbers – 300 million and 100 million respectively. Koum's criticisms are well founded. Registered users are more abundant but not as valuable as active users. Plenty of people download an app such as Line once and never it use it again. So it pays to be skeptical any time you see a company touting enormous numbers of registered users. Such companies are trying to make it seem like their products are more popular than they are.

But skepticism is warranted of WhatsApp, too. You have to wonder why the company, which prior to 2013 barely said a thing to the press, has been so outspoken. Is it worried?

Line, which has been around only a couple of years, might have far fewer active users than WhatsApp, but also has a hell of a business model. Through its sticker sales, virtual items, and associated games, it reached Q3 revenue of $157 million, up from just $10 million a year prior. While Kik hasn’t disclosed revenues, it has built a platform around messaging that provides a clear differentiator from WhatsApp, which has insisted on a minimalist, messaging-only approach to its product. Kik’s “cards” – HTML5 Web apps that can be anything from games to photo albums – have been installed 145 million times since they were introduced in November 2012. Zynga’s “1 Word” Kik game was reportedly installed 1 million times in the space of 24 hours.

WhatsApp, on the other hand, is limited by its model. So far, it makes money only by charging $1 to use the app. It has no games tie-in. Unlike China’s WeChat, it can’t hope to be a force in payments. There is no platform upon which developers can build. It offers nothing in the way of an ecosystem in which anyone other than the company can share in the benefits from its huge user base. It's just a messaging service.

That might turn out to be the right play. Perhaps the trends will break in its favor. People may decide that, ultimately, all they want is one service that does messaging really well. Still, there has to be a lingering suspicion – if not an outright conviction – that messaging alone is not enough, that one day WhatsApp will look back and ask what happened to those 400 million active users.

Line, Kik, and WeChat are showing that it is possible to build a compelling social and communications service off the back of messaging, but not limited to messaging. There is every chance that WhatsApp will ultimately find itself a deserted island, bereft of attractions that its competitors built in acknowledgement of a new era of mobile communications.

WhatsApp’s dilemma is reminiscent of social networking’s early days, when MySpace, convinced of its dominance and user numbers, obstinately held out when it came to letting developers build on top of its system. Ultimately, it had to sit back and watch as Facebook executed better and opened up its platform so that others could build upon it and improve the service (even if its utopian vision of total openness was short-lived). This gave Facebook an edge over MySpace, which failed to recognize the importance of fostering an ecosystem. The one-time frontrunner eventually saw the world around it evolve beyond it. So the question is: Is WhatsApp MySpace or Facebook?

It would be foolish to say that what happens in mobile will necessarily follow what occurred in the desktop social networking age. It might well turn out that the world wants one app that does a great job on messaging and nothing else. In that case, WhatsApp would be golden. But if not? Line, WeChat, KakaoTalk, and Kik are building powerful platforms around their messaging experiences. Chat is just a front door to an alternative kind of Internet, in which social networks, games, communications, payments, and ecommerce can all be rolled into one app. Someone can win big in this space, just as Facebook won big in the social networking era.

Given WhatsApp’s early lead, and that jaw-dropping 400 million active users stat, it would be foolish to write off the company. But of all the messaging products mentioned in this article, it is the one I’d least like to be. Just a messenger. No platform play. No hope of being anything more than a sender of SMS and voice chats.

And, maybe, no hope of winning the messaging wars.