Sure there wasn't messaging between systems, but the point was I had friends on AIM, YIM, and MSN and I could use one program (with three accounts signed in) to

Sure there wasn't messaging between systems, but the point was I had friends on AIM, YIM, and MSN and I could use one program (with three accounts signed in) to message them all and not have to think about it. Adium would just aggregate them together, so I'd see "FirstName LastName" and it would message from the right service. But modern chat apps like FB Messenger, Google Chat (if it still exists?), etc. managed to successfully break all that, never worked reliably in Adium or Pidgin (if at all).