Unlike other social products, WeChat does not only measure growth by number of users or messages sent. Instead they also focus on measuring how deeply is the product engaged in every aspect of daily life (e.g., the number of tasks WeChat can help with in a day)."
100 times this. I can't think of a single large Western consumer software company who can actually think like that.
It has become a commonplace that WeChat is incredible, and everyone over here wants to build it. But solving that problem is hard. Really hard.