"So should I un-friend that girl I met at a party five years ago but haven’t spoken to since? Oh wait, you make that nearly impossible. Plus, how then will I know that she needs my help to kill a rival Mafia?!"

If you no longer care about someone's updates or anything that's going on in their life, you can remove them as a friend. I know tons of people who have removed people from their friends lists. Or if someone plays too many games and you dont like seeing that update on your feed, mute those types of posts or posts from that user.