Sure they would. Does that mean it is good for the ecosystem on the whole? No.
80% of internet.org users are users with existing data plans. How hard do you think it is to get someone switch over from free to paid? Even for a person of privilege, he will prefer a free meal over a paid meal unless there is a huge difference in quality of a free meal (e.g. bread) vs. paid plan (e.g. steak). Considering that only well capitalised companies can provide free meals, you have just made the uphill battle that startups everyday fight against BigCos into a vertical slope.
It doesn't have to be like this. The Delhi Government is going to soon roll out a free neutral Internet covering large parts of the city. There are many models of free Internet implemented all over the world.
We'll get connectivity to the millions, but it won't be on Facebook terms - it'll be on the terms as decided by a democratically elected nation.
We are agitating to ensure everyone else gets the full internet, not just Facebook. It's not that hard. The government already collects 5% of all telco revenues for a "universal service obligation fund" and has not spent it. The money sitting in that account alone could give everyone internet access.