The majority of the content on my Facebook feed is links to external websites. I'm skeptical of this argument that poor people will be forever satisfied with just chatting and browsing Facebook and will never upgrade to full internet.
A lot of users in these countries answer yes to the question "Facebook is the internet", and claim they never follows links out of Facebook. Of cause these answers reveal widespread ignorance, and it may be that they don't know if they leave Facebook or not, but it does mean that Facebook is the gateway to Internet for them. Thus a lot of users will stay satisfied with internet.org, especially if that is what most people in their local communities use.
[1] http://qz.com/579502/the-winners-and-losers-of-2015s-10-most...
AOL's walled garden didn't stop people exploring the big wide world, it was a gateway drug.
For many it may have been a gateway to facebook ;)
Not sure if you are joking, but with features like "Instant Articles", Facebook has every reason to keep people on facebook.com rather than sending them to external websites.
When you are locked down in a walled garden that allows messaging (within the garden) and every other service is blocked, people will simply believe that walled garden is all there is.
It's not just Facebook that's a part of Free Basics, it is Facebook, Wikipedia, and a bunch of other services that are "approved" by Facebook. So the chance is greater that people will become used to these free services (not just Facebook) being perceived as the Internet.