I've been thinking about quit Facebook a lot, It causes lots of issues, however I don't do it yet because I use it for the bounties campaigns.
I think facebook is not just for dev bounty campaign alone, with us using facebook, we will know the latest news today from all over the country. by using facebook you can notify or know the condition of your family and friends wherever they are even though have not met for years. so in my opinion not everyone can get out of facebook.