>> 1) The core product is good and useful to people/society.
Definitely not. If you had to put a numerical value on Facebook impact on society, it would be extremely negative I think. You grab attention of weak users, that end up spending so much time on your platform doing nothing instead of contributing in things that would benefit society. You create an illusion that everyone got a beautiful life, pushing some people on the verge to suicide//depression. And maybe the worst of all, you block free speech based on whatever private criterias you decide and you allow for mass brain washing by pushing ideas on your newsfeed. The only positive side is your utility of connecting people which already perfectly existed before.
The only reason why you get away with all of this is because it is so difficult to put an actual number on those.