The point you are missing is that it's not about
> "having no internet at all"
because what Facebook is offering is anything but the Internet. It's not even close to being the Internet.
It is Facebook's walled garden which they control, they decide what lives there and what remains, what gets kicked out.
You know what is worse, it is not that Facebook is providing something that is not the Internet, but the worse is - it will give a precedence to such business practices that may effectively kill the Internet as a medium, as we know it today, in India and turn it into the cable company model commodity where we have to buy packs of "access X, Y, Z services at speed A", or even "access sites X, Y, K" when there is another pack "X, K, M services pack".
It will affect innovations, new services in a drastic manner. Can you imagine what the status of Facebook would have been if the Internet all over the world was in a way that provided Orkut for free because Google paid for it by including it in its "Google Free Basics" pack? I don't think Facebook would have been here at all.
Now, let's say Amazon arrived in India before Flipkart, Snapdeal (Indian e-commerce portals) and jumped on an "India Free Basics" plan and now people have free access to Amazon but this guy in Bangalore who started Flipkart couldn't afford to jump on that "India Free Basics" because hey, they didn't have deep pockets from the beginning. The list of what-if examples can be endless here, I just hope you get the idea.
> Nobody else is going to give full internet to them for free.
Indian Govt actually provides highly subsidised Internet in rural areas and is working to make it more accessible. And ideas like Facebook Free Basics are actually going to harm such initiative by the Govt giving them a reason that people already have "Free Basics". I mean not saying this is how it's gonna end up exactly but let Facebook and Network operators have their way right now and something similar is waiting for us in the future. Sounds like a mild dystopian story? Well, read about "license raj" in India and related stories.
> They will be stuck with nothing.
No, they won't. They will get the Internet, maybe few months, or a couple of years down the line - slowly (and this is already happening) which is better than not getting "the Internet" ever, or when it's too late.
By the way, what stops Facebook from kicking WikiPedia and Khan Academy out (let's just say they are there) later on and rather bring Snapchat, Vine and Instagram in its place? Now, you may say it's better to watch cat gifs and share selfies than having "no Internet at all", where again you'll be missing the point that "this is NOT the Internet" and that line of thinking is unfortunate in my humble opinion.
A lot of these points have been covered in these videos by a local standup comedy group (in order): https://youtu.be/mfY1NKrzqi0, https://youtu.be/W0w_YhZUYeA, https://www.youtube.com/watch?v=AAQWsTFF0BM