It's one of the largest employers of people like us, they have tremendous mindshare as virtually everyone is a user and in one insidious way or another they form an important part of the net as a whole (see, "sign in with fb" or "comment with fb" or "like on fb").

Why do we care about Facebook is tantamount to never covering any large internet company which I might be OK with but I suspect is not what you're arguing about.

It might be worth a conversation about why the HN filters are tuned so that I hear so much about Snapchat and I never heard a single word about the Climate Corporation - easily the most exciting startup I've seen, right up until they sold to Monsanto.