It is a symbol of status within the community that you are building, that they are given a sort of acknowledgment for them hanging out with you.
What draws people to your channel is the content of your video, and the way you present yourself.
All social media, up-to-date services, and platforms try to win over your time and engage in a conversation.
They can also put links in the chat when they are disabled.
A moderator is an individual that you trust to act in your stead to bring the hammer down on unwanted behavior on your channel.
You can also filter so that all moderators or all editors appear, as you need.