> It does make it a good thing for them. Which begs the question: why is it that you get to decide what is or isn't a good thing? Or: why shouldn't people be able to decide for themselves? The answers against the latter are, at their root, paternalistic and elitist.

I'm not clear on what your argument is here. Are you:

* denying that there is a fact of the matter about whether, for any item X, X is beneficial or harmful?

* asserting that something's being beneficial or harmful has no meaning apart from signifying present-day user preference?

* merely asserting that users fairly reliably tend to prefer what is good for them, and avoid what is bad for them?

> Billions of people like using the product and it hasn't hurt their lives. In fact, it has improved them.

It sounds like you are making a case here that Facebook is beneficial because it improves the lives of its users—am I understanding that correctly?