My social life is on WhatsApp groups. No one in my social circle uses Facebook Messenger for anything relevant. The number of friends' photos has steadily gone down over the years. I've switched off FB but come back when am bored and want to spend time looking at cat photos and BuzzFeed. Facebook not existing in the world would impact me minimally.
Google, and even Microsoft, on the other hand, damn if they stopped existing... I'd be fairly distressed I suppose.