1. Facebook knows about all of your interactions on Facebook, and they probably know what you are buying and what sites you visit through tracking mechanisms. In real life we call those people stalkers.
2. What utility are they really getting? Is keeping up with every part of your friend's life (or the good parts they show you) really worth the stress and anxiety of feeling like you are missing out? It's fake utility. People somehow existed for something like 300,000 years without this utility, so what value is really there?
That being said, it's designed to get people addicted and the immediate "utility" is a lot stronger than any abstract worries, so there's probably nothing you can say.