None of the chat messaging platforms interoperate. Chat should be like email, but everyone just wants to push their proprietary app consuming battery power and storage.
The golden age of chat was back when you could use one client to talk to all your friends despite them being on ICQ, AIM, MSN, IRC or half a dozen smaller networks.
Trillian! It was nice to use a single client for ICQ, MSN and others.
Universal availability and plain one-to-one & group chat removes most of the issues. Less important to support things like file transfer, voice chat, etc.
Who could combine Skype, WhatsApp, FaceTime, Hangouts, Discord, Microsoft Teams/Skype for Business, etc. and do it in such a fashion I can trust it.
Damn, I don't like government regulation, and when it comes to chat I'm frankly scared — I don't think they could resist the urge of adding backdoors in the process. But who else could put some pressure on the vendors to get these things to interoperate?
Adium for the Mac folks! The website is still there (https://adium.im/) but the version history page is an error and the product blurb talks about AIM support, so I'm guessing it's dead.
Chat will never be interoperable because then vendors wouldn't be able to introduce their own exclusive emojis or GIFs or stories or whatever other nonsense.
