There are some things you can't hide for the internet to work, such as IP addresses, so an IP address on it's own is not privileged information. Announcing to the world that "this is my IP address" adds information and context which from a privacy perspective is privileged. If someone has an issue with you, they might target their focus to seeing if there's a service running which is vulnerable at your IP, or they could initiate a DDoS against you.