Private Real Time Communication

I'm still a little confused about how SimpleX works without userids, even after reading through the material. I assume it operates around "chats" rather than users? That is, participants wouldn't necessarily know that I'm the same person in two different chats I'm involved with? But then you'd have to have some way of initiating the chat "physically"? And wouldn't something about my messaging routing history "signature" be the same in two different chats I'm involved with?

I've always wanted to see Briar get more attention although I understand the reasons why it maybe hasn't.