I always said that Facebook can innovate in different ways:
1. use their already existing social graph to produce OTHER apps that are useful
2. use their tool with a new social graph
Number 2 has been done once I believe. It's called workplace. Number 1 is what Wechat is doing on steroids, and Facebook has done almost none of that. It's insane that they're not taking advantage of this and are just adding noise to the useful tool that facebook used to be.