Can you genuinely not see or are you just being disingenuous?
The mechanism this would work by is ignorance, if someone is unaware that they only have access to a tiny subsection and believes that they have internet access (and we all know plenty of people that thought AOLs walled garden was the internet) then they are less likely to seek out real unfettered internet access.
Reckon Facebook are going to have big banners up telling them this is only a fraction of the net? I very much doubt it.
If you're so against an open internet what are you doing on HackerNews? Surely there is somewhere you could post about this on Facebook. Oh wait a second you love having access to the whole internet you just don't think people poorer than you deserve it.
So that should be addressed by education and banning misleading advertising, not by banning the program altogether.
Did I say I was against an open internet? I'm against government regulation of the Internet, while the people arguing with me here are in favor. There's more than one way to frame this about "open".
I could also snarkily ask you why you don't think the poor deserve to have access to anything, which is what will happen if internet.org isn't allowed.
If you really think that poor people deserve free internet, start a charity that brings it to them. But banning other providers from taking gradual steps towards internet access won't help them.