Facebook has become an indispensable app for the very low end $40-45 android smartphones. Such as the ones you can see for sale on AliExpress with 3.7" screens and Android 4.4 running on a very cheap MediaTek chipset.

People who buy these in developing nations usually require that the handset retail vendor install the .APK for Facebook (though they don't know the process of HOW facebook gets installed without the Play store, they just know that "I want facebook on my phone), before buying the phone.

http://www.theatlantic.com/technology/archive/2016/01/the-fa...