Most major vendors did use it, and likely still do internally, but with federation turned off. If you have a billion “users” using a working chat system and th

Most major vendors did use it, and likely still do internally, but with federation turned off. If you have a billion “users” using a working chat system and the concern is “with federation they can chat with outsiders and we can bleed users” you don’t just drop the whole thing, you turn off federation and prevent third party client logins.