"your coworkers aren't your friends" is a thing that came to us along with industrial revolution. When you live in a small village during medieval times you're going to be friends with everyone, whether you like it or not, and you'll spend most of your life working with your immediate family. But when industrial revolution came, people started working together with strangers in giant factories. And let's be honest, from the perspective of factory owner, it's best if strangers stay strangers. If they start getting buddy-buddy with each other not only you'll see workplace conflicts, but also they might organise and demand something.