Facebook's meets "skepticism" because it is offering walled internet in South East Asian countries like India, Indonesia, etc. Facebook + a few services that people didn't ask for. Clicking external links on Facebook will lead to a page warning that you will be charged if you visit a service that's not part of internet.org. Google has also been offering such a service called "Google Free Zone" in certain countries.
If Facebook or Google feel so charitable, why not help telecom providers write-off data costs and offer say 250mb/month free per person?