And that’s a problem!
After about 30 years we see a clear pattern: something like AIM comes out, because it is locked in there is no competition for the client or the server so there is no motivation to improve either. The thing is the computing world moves ahead so the system goes bad like cheese as the environment it works in changes. A decade later there is a new client out and people are saying “Remember when AIM used to work? There’s a new service that works just as well as AIM used to work” and finally people are so burned out of AIM they are ready to switch but failing messaging systems can lumber on for years like that.
Emphasis on “just as well” because in this scenario the systems are not getting better, you’re not getting an upgrade by switching, you’re just treading water. What people aren’t realizing is that if we had interoperability we would have had competition and after 30 years we’d see 30 years of progress in messaging systems unlike the occasional churn but lack of progress we’ve had.