The downside is only the "gatekeepers" have to provide this interoperability, when it would be far more useful if all the popular platforms were facilitating it.
Still I agree that pre-2012 IM status was much better when open protocols were more popular. Of course there was the Windows Live Messenger thing but even you could use something like Pidgin to chat with it.
>In order to maximize user security, we would prefer third-party providers to use the Signal Protocol. Since this has to work for everyone however, we will allow third-party providers to use a compatible protocol if they are able to demonstrate it offers the same security guarantees as Signal.
>To send messages, the third-party providers have to construct message protobuf structures which are then encrypted using the Signal Protocol and then packaged into message stanzas in eXtensible Markup Language (XML).
>Meta servers push messages to connected clients over a persistent connection. Third-party servers are responsible for hosting any media files their client applications send to Meta clients (such as image or video files). After receiving a media message, Meta clients will subsequently download the encrypted media from the third-party messaging servers using a Meta proxy service.
You also have to connect over XMPP and through a proprietary "Enlistment API", etc.
https://engineering.fb.com/2024/03/06/security/whatsapp-mess...