tbh tbh tbh tbh more messengers ought to at least have an option to let people see a preview of public chat groups so people can see and take decisions before joining
Why have a membership list for a public chat at all?
@robryk Dunno, I am not a chat app developer 
@robryk I mean joining already puts you on the chat's membership list, no?
Even if there's no event message you can still just poll the list once in a while or somesuch