In 5401 an alternative decentralized chat system was introduced that allows chat functionality without reliance on any centralised servers.
Although the centrally managed friends infrastructure was removed in Vuze 18.104.22.168 the underlying tooling still exists and is functional. See 'Classic Friends'
What is the difference?
Decentralized chat is a channel based chat system - as a user you need to select and join channels to communicate with other users. Channels are automatically created for things like downloads, tags and subscriptions.
Classic Friends is a user based chat system - as a user you need to find other users and exchange keys with them to allow communication to take place. Once you are friends with another user you automatically get features such as 'speed boost' - preferential uploading/downloading with your friend when downloading the same torrent.
You can use decentralized chat to find people that you want to be friends with and then exchange keys via a private decentralized chat session (for example)
Currently classic friends uses encrypted traffic over the public internet to communicate - there is no anonymous option although if there were interest this could be developed.