Imagine someone in the slums of India (there are tens of millions in these conditions) wanting to learn more about irrigation. Is it more important that they have no limited internet for the sake for competition, or limited internet?
Why not give X megabytes/month data to the user for free and let HIM chose what the "essential internet services" for HIM are? Internet.org is a non-profit so it would be completely fine giving it for free. But even if they wanted to recover their costs, they could do it in a neutral manner - by ads.
Even with your premise accepted, there are better solutions. Internet.org's current model makes sense only when you consider the ulterior motives as well.
This is something that's totally compatible with net neutrality while providing the same benefits you're advocating.
Even without that, thumb drives are usable with smartphones via OTG cables.