Different audience. People went on the internet for the first time for facebook. A lot of people never leave the facebook ecosystem. Having a phone that didn't have facebook would make it less popular.
A phone not supporting flash might get developers upset. But by that time developers wanted html5 to take over and developer preference doesn't push product.
One can make the case that the most inexperienced with computers person is Apple's ideal customer / most profitable. Not being able to get on facebook would push this demographic to other phones.
Wasn’t FarmVille and applications like them Flash based?
You also have to remember even as late as 2011, Motorola was trying to sell the Xoom tablet as being able to browse “the real internet” because it (belatedly) supported Flash.
But then we still get back to the fact that in 2008, the iPhone 3G had 128MB RAM and couldn’t even fully load a regular web page. When you scrolled to fast, there was a checkerboard while it tried to render the rest of the page. It definitely couldn’t do any complex animation within Safari.
A phone not supporting flash might get developers upset. But by that time developers wanted html5 to take over and developer preference doesn't push product.
One can make the case that the most inexperienced with computers person is Apple's ideal customer / most profitable. Not being able to get on facebook would push this demographic to other phones.