You have probably heard it said that Captains' success is directly related to their relationships with the people working for them, the people working with them, and the people they work for. This is true. Friendliness doesn't mean being your crew best friend, or forgiving bad performance, understanding personal problems, inviting them to your room, lending them money, or letting them do what they want to do. They smile a lot, they are easy to talk to, they are polite, thoughtful of others, and considerate as they perform their management interventions. It just seems so natural when they do it.
Some people are only friendly to their dog.
Maintaining a friendly relationship is another part of maintaining work performance. It also helps you avoid having people try to hurt you because they don't like you. It might save your life.