This underscores what appears to be an interesting strategic move by Facebook: build an ecosystem of applications, which in turn encourages people to use their other products. In turn, this provides continued competition against Twitter, Tumblr, etc.

The interesting thing about this app is that it's an experiment: viral success of social applications appears to be a hit or miss sort of thing, so why not throw many things at the wall and see what sticks á la Paper, Home, Messenger, or buy something already big á la Instagram or Snapchat.

One benefit of this strategy is that it raises barriers to entry for your competitors: the more modes of social interaction you offer, the fewer opportunities for your competitors to chip away at your empire, and the more enticing your properties become to advertisers.